Just wondering how many travelers use dual passports? As I am an Australian with an Australian Passport and can also obtain a Malaysian Passport as well. However the Malaysia does not allow people to hold dual passports. Wondering if there are any advantages to get a Malaysian passport and how to use it without getting caught out.

Mrs P was born in Malaysia and so had a passport, but let it lapse when she became an Aussie.
I'm pretty sure that Malaysia is one of those countries where - if you willingly become a citizen of another country you automatically lose citizenship of that country. (Australia used to be the same - remember Rupert Murdoch lost his Aussie citizenship when he became a yank.)
But if you're born with dual nationality, then I expect you can keep them both?

Me - I have three current and valid passports - British by birth, Irish by ancestry, and Aussie by choice. Use the Aussie one for entering and leaving Australia and either of the other two for entering/leaving Europe. For other countries I shuffle them and pick one

Generally there is value in carrying a second (or third) passport to enter a country where diplomatic relations are better or where visa requirements are less stringent. When I went to Turkey last year my friend entered on her NZ passport as there was no fee for the visa for her while I was stuck paying $20 for mine. And you are supposed to enter a country where you hold a passport using that country's passport. Other than that, not too big a deal that I can figure out.

As for "sneaking" a second passport that you aren't supposed to have, I wouldn't go there. I don't see the upside as being good enough there for the risk.

Does a Malaysian passport get you anywhere that an Australian wouldn't?

I don't see much advantage to it over an Aussie.

Like with many other former British colonial holdings, Malaysian law generally prohibits dual citizenship for Malaysian nationals.

If making a choice between Malaysian citizenship and Australian citizenship and basing it on the utility of the passports for travel, then I would say that the Australian passport would generally be far more convenient for far more travel (without visa fees) than a Malaysian passport.

In some cases, the Malaysian passport means lower (or no) visa fees compared to Australian passport; however, that's more the exception than the norm given that Australian passports are good for entry without a visa in advance at a longer list of countries than Malaysian passports.

And if the OP does not foresee going to any of those countries it is a moot point. If the OP travels to those countries regularly then that is a different story.

I have two US passports: One that I have used for visiting Islamic countries and one for everywhere else, including Israel.

My wife was born and raised in London. She still has her UK passport but doesn't use it--especially in coming in and out of the US, where her US passport is far better.

So if it's possible to have two valid US passports, what is stopping the bad guys from doing the same, and why bother with the "security" circus...?

Yes... a lot of countries allow for duplicate passports. If you have an Israeli stamp in your passport you can't travel to a lot of Middle Eastern/Arab countries.

We have said basically the same thing. There are some countries where it's cheaper and/or easier and/or better to use a Malaysian passport than an Australian passport, but the Australian passport is generally far more convenient for purposes of travel across more and more frequently visited countries.

Until people failed to read things in context, this thread was about dual citizenship and not dual passports from the same country. But in carrying on with the digression, there is very little to stop "bad guys" -- at least those who have their wits about them and are willing to spend a little more money to commit fraud -- that lets them do the same.

Legitimately, it's possible to have two valid US passports or even more than two valid US passports. Some Americans have had up to five valid US passports at a time -- but probably that is generally more likely to involve Americans who do not hold dual nationality than those who legitimately hold passports from a second country.

When it comes to entering the US, US nationals are required by law to enter the country as US citizens. Use of different passports (in the same name) of the same type by a US national won't make a difference as the US passports are now generally linked to the same named person regardless of which US passport is being used to re-enter the US.

To the OP: if Malaysian law does not allow you to hold a Malaysian passport because it doesn't consider you a Malaysian citizen since you are an Australian citizen (and I say "if" because although that is my understanding of the Malaysian position I don't know that for certain, but if it is true), then you will be holding a Malaysian passport that is technically invalid, so my advice would be to be very careful...

That is true for many countries, but not for all. The US, for instance, insists that its citizens use a US passport to enter the US. South Africa and, in almost all instances, Australia have similar requirements.

But the UK, for example, does not, and merely requires that the documentation presented at a UK port of entry is adequate for the purpose of the trip. So there is nothing to stop, say, a dual Botswanan-British citizen going to the UK on a holiday using his or her Botswanan passport and entering the UK as a Botswanan citizen. Generally, though, the only thing that the UK will put in the non-British passport of a British citizen is a right of abode certificate: they won't knowingly issue a visa to a British citizen.

Other countries that do not in all circumstances require their citizens to use the "home" passport are quite numerous, and include Ireland, France, New Zealand, Canada...

Malaysia's indigenous people -- just like the indigenous people in many other former British colonies in Africa and Asia -- insisted at the time of independence or soon after independence on rather strong prohibitions against holding more than one citizenship in order to try to break the ties between the (former) colonists and the land they (or their parents/grandparents) colonized.