Creative Inventory duplicates to 64 whenever picked sometimes (Also appears in servers)

Sometimes when I go to my Creative Inventory, I sometimes pick a stackable Item or block to my hot-bar. However, I get a stack of 64 of the Item or Block and I am unable to put it in my hot-bar.
This may occur a lot with servers at people on creative mode.

NOTE: This glitch is not that rare (about 40%) .