I am a blender novice but cannot find out about this problem.
I am sorry if the problem is simply my lack of understanding and hope it does not take too much of your time to verify this issue.
Operating system: Windows 10 Pro 64-bit
Graphics card: 4095MB NVIDIA GeForce GTX 1080 (NVIDIA)
blender-2.80.0-git.0264d8390fa2-windows64 ( + all previous blender 2.8 tested to date)
Short description of error
A plane has cloth physics enabled.
end time in the (cloth physics) cache is changed to say 1000
Several duplicates of this are made.
Duplicates resort to 250 end time.
Cannot copy end time to selected duplicates either.
Only way to change end time for all duplicates is to do it one at a time manually.
Exact steps for others to reproduce the error
create a plane which is pinned at top so that it drops in the z direction
add physics cloth to this plane.
(I also enabled object (not self) collision but I don't think this is important).
Change the cache end time for the cloth to 1000
Duplicate the cloth (plane) several times
Then try to make the duplicates have a 1000 end time in the cache.