Marhaba does offer baggage transfer, they do say it's an an additional cost so best to enquire with them, you can do this by e-mail on their website.

I don't think it's possible to check in a 2nd item airside at DXB, that being said I almost always travel with two pieces of hand luggage, a hard-shell suitcase (within size limits) and a laptop bag, sometimes requires a bit of hide and seek to get it onboard, though. Especially on India flights.