Originally, if I tried to put a duplicate infusion on an item (e.g. 2 conveyance infusions on the same gun) it threw an error message and greyed out the empty slots. Last night, I discovered I can put duplicates/triplicates on an item.
Couldn't find a mention of this changing in patch notes, but I know some things (such as item stacking) were intended but didn't get mentioned in the notes so wanted to check if multiple copies of an infusion on the same item is intended before I reported the bug.