For some reason, whenever you logout then login again the world, or even Realm, the enchanting table keeps giving one single list of enchantment every times as starter.
MCPE-26046
Enchantment Get Reset
Resolved
Duplicate
0
Thank you for your report!
However, this issue is a duplicate of MCPE-22554, which was fixed in 1.2.5.52. If you are still having this problem, please attach a comment to say so.