With multiple double tags I accumulated 5 negative tags from a skip. Only 3 of those got applied to the next shop (my shop limit was 3 cards) and the remaining 2 negative tags were left unused. They did not trigger when I got to the next shop, but remained in inventory.
On the next ante I got a doubled up D6 tag that were shown on top of the 2 unused negative tags. In the following shop one D6 tag activated and 1 of the leftover negative tags activated. I then re-rolled in the shop, and the last negative tag was used up.
It doesn't seem to use the negative tags in an expected way, not triggering the additional negative tags when I entered a new shop until I got another tag and even then only activating one of the negative tags.