About personalize content,I found our users to personalize content as the following way,and caused there are multiple redundant block on preview model,I can't figure out the reason.
ContentArea has both an Items collection which gives you all blocks and a FilteredItems collection that also filters items based on visitor groups and access rights etc. Might be worth checking that you are using the FilteredItems collection when rendering your blocks?
@Daniel,Thanks for your help.I'm sure that user used the visitor group and here it's not access right. and our user said that it works before updating version 9.5.