Soldiers Serving in Multiple Service Branches in WWII

[AJFFM]

I recently was reading a bio of Shelby Foote and apparently he served in the US Army in Northern Ireland and was dismissed after a court Marshal only to go and volunteer in the Marines. In both cases he saw no combat.

I also noticed this in the British Army with several people serving both in the RAF and the Army or the Navy.

How common was that?

Did something similar happen in Germany and the USSR?

[wbfamily]

My opi served in the kreigsmarine and the mountain troops. I don't know how common it was but in his case, it happened!