I found these two sets of glasses online. I have done some research but can't determine if these two logos belong to the same brewery or to two different ones.
I'm going to take a guess that you're looking at a German-labeled set of glasses and a set made for English-speaking countries. I see no reason that the brewery couldn't use different logos too. If you go to the brewery page here on BA (link below) and click on some of their beers that have pics shown of the labels, it looks like neither of the logos from the glasses is used, at least for the 4-5 pics that I looked at. The brewery is listed as Closed here on the BA site, and I didn't try to find any internet historical websites for it. https://www.beeradvocate.com/beer/profile/921/
Looks like they used the second logo on keg labels (below right) when the brand was exported to the US in the early 2000s. Around that time, one could have gone to a Food Fest sponsored by the brewery way up in northern California and maybe even got the chance to meet the Birschoff Girls.
The first set are just older, I think. There's a brief overview here: https://www.inside.beer/news/detail/germany-150-year-old-private-brewery-bischoff-has-to-close It only closed a few years ago.
