I've been asked to accompany a local choir on my baseguitar and in the notes they sent me, I have found two chords notated above one another (see image below). This is not the first time I've seen this, but I was never sure what exactly to play in such a situation, so I decided to investigate. My search was largely unfruitful, and I have only found two different situations, where two chords would be notated at the same time:
The first one is the Slash-Chord, usually notated as e.g. Fmaj/E, the other the Polychord (as far as I've understood, this is a jazz chord where you essentially play two or more chords at the same time). Sadly, research of neither of these did mention anything of the type of notation I've found.
My Question now is: can anybody tell me what this/these chord(s) mean and what I should play.
PS: The piece of music is "in german" (we have some peculiarities in our notation, e.g. the "B" in the image actually being a Bbmaj -- a B would be written as "H". Maybe my problem is a similar german-only thing?)