There is no one-to-one *link* between an Admob account and Google play account.
In your Admob account you create AdUnits whose Ids you reference in your app.
You deploy your app to a particular Google Play account.
There is no problem using multiple AdUnits (perhaps from different Admob accounts) within your app.
This is a common pattern where 2 developers are attempting to share revenue.
But I am not sure of the legality of having 2 Google play accounts - regardless of the use of Admob.
Better get a lawyer son :-)
William
**Not a Google/Admob employee**