Now this is based on memory over the past few years, but I remember this phenomenon of getting the 15 nights from both the personal and business cards (for a total of 30 nights) to be inconsistent. So if you pursue this with Marriott, YMMV.

If I remember correctly, over the past couple of years, some people have posted about not getting the second - 15 night bonus. Then when they have investigated it, Chase reported the info to Marriott correctly. However, the Marriott computer processed it as a duplicate transaction, and voided the second 15 night credit. I believe many of those people never got their 15 nights for the second card.

Hopefully, this is not the case with you. But I have dealt with Marriott in cases where their computer throws out a similar transaction as a duplicate. It usually involves multiple calls to the platinum desk, and they end up posting the second transaction as goodwill points. So the actual problem of the computer flagging it as a duplicate transaction was never fixed. They just did a manual work around. This happens to me with Hertz rentals. If I have 2 rentals during the same week that each qualify for a 2000 point bonus, one of the two usually doesn't post right. The problem isn't on Hertz's end. The problem is that the Marriott computer flags it as a duplicate.

Good luck! I hope you get your nights!