I just did a search on this page for "activeTabCookie" and I only found the three instances right below, so I think that either means that

(a) you moved something and forgot to remove it in the original location (I suspect and hope it was this)
(b) you created a copy of something when instead it should be adapted so a single copy can be referenced from both pages
(c) you created a copy of something that legitimately needs to be copied because the copy needs to diverge from the original in a way that can't/shouldn't be subsumed into one instance, in which case the fact that it was copied from something else doesn't justify anything having to do with the code you added.

The general idea of justifying not improving code because you copied it from other code that was already like that is terrible for the health of the project, because it 

- proliferates the code that should be improved!
- makes it less likely that anyone will ever improve it

Instead, it's better to improve the code before you copy it, or figure out how to make a single copy handle everything so you don't have to deal with a bunch of different copies.