I built a second base in C America, the first being in Middle East.
I added 8 troops to the second base, and later on began to train 2 of them.
Upon trying to allocate troops for a mission, I found I could only allocate 5 of them.
On entering the battlescape I found that the Chinook contained duplicates of my troops.
I have been able to complete two missions from this base with no crashes.
Possibly related to transfer bug reported earlier, but I didn't see any note of duplicate troops in another thread. Will post screens/save game when I get a chance.