The reason why you now see two systems in UAT is that when you are transporting a group, the transport tool also takes the attached system configuration and includes it in the transport request. Now you have both the DEV and UAT system configured in UAT, which most of the times doesn't make sense.
That's why I always advise NOT to transport groups, but to build them manually in each system. It is unlikely that your users / authorization settings / PFCG roles in UAT will match the same in DEV, so it is always better to just set up the group in the environment they belong to.
I'd advise to remove the superfluous system config in SPRO and delete the group, then set it up in UAT.
As for the flavors, after transport you'll have to adjust the system assignment using the admin transaction. Get rid of anything that doesn't belong to the target system and you'll be OK.
