Intended behavior, see the most recent #news post in Discord.

 

I cannot reproduce this with instant healing potions. However, I can reproduce this with an extended potion of swiftness (Potion#fY).

Same behavior as in the video: Repeating /if add on the same item adds it multiple times to the filter (which is not the case with instant health for me), and the filter does not actually prevent me from picking up the exact same potion.

Spoiler: /if menu

All four swiftness potions in the filter resulted from repeated /if add on the same item. The red healing potion worked properly and was only added once.

 

I am unable to reproduce this issue with health potion, but I am having a similar problem with tools and fire resistance potions. When I have the same item in /if menu 2+ times, the filter stops working.
On a related note, though the iteminfo for tools with different durability is technically different, I would still expect one item filter to filter out the tool with any durability. It would be really annoying to have to add a filter of an item for every durability.