LukasSMSFT your posting confused me...
running Get-Command Exsetup.exe | ForEach {$_.FileVersionInfo} on both servers show:
ProductVersion FileVersion FileName
-------------- ----------- --------
15.01.2507.021 15.01.2507.021 C:\Program Files\Microsoft\Exchange Server\V15\bin\ExSetup.exe
ONLY the AdminDisplayVersion differs between both servers (one with 1st and 2nd release of the update, and the other server with the 2nd release of the update only).
Server #1: Version 15.1 (Build 2507.18)
Server #2: Version 15.1 (Build 2507.17)
Do we have to fix one of the servers? The servers are in different customer networks, running in different ADs - they have nothing to do with each other.
...or could we wait for the next CUs/SUs so the AdminDisplayVersion will be raised to higher values with the next updates?