Patriot rebels turned into countries army

[JellyRev]

I used some some Patriot rebels in Austrian land. The Rebels successfully rebelled against Great Britain but became part of Austria. Austria declared war on me(Italy) and sieged one of my provinces. I took my stacks over to attack this stack but they could not fight. I noticed Austrian Troops had an Austria flag/Italy flag instead of just one country. This allowed me to occupy all their provinces and they could do nothing to me as they only had one massive stack.
Is this a known bug? or was this put into the game on purpose?

 

[Dathon]

This is intentionally as you are the funder of the patriot army. They are friendly towards you and considered allies(hence the dual flag). In your case it aids you, but rebels running rampart on a ally or vassal can be devastating as you can't rush in and help them fight the patriots as your armies won't engage them(with the result that your ally or vassal might break etc).

 

[hitchens]

If they had a different flag they had formed another nation.