The first few times it happened it was fairly spread out time wise, so I dismissed it as a happy bug, a boon.

But, lately it's been fairly consistent.  Maybe 20% of my turns?  All on different computers, but almost exclusively on Google Chrome.  (Not a comp. guy, don't know if that makes a difference.)

Anyway, getting double the amount of units you should be getting can have a serious impact on the game, probably something that should be fixed. 

Can you let me have the links to the games involved so I can take a look please? Also ideally the turn number where it happened...

Some boards, like World War, allow Reserves which means you don't have to place your untis that round but can save them for a later round.  So are you sure you just aren't accidentally storing them in Reserve until the next round?