Obviously personal choice evidenced by the responses here. I agree with alurid and keep one on each side of the radar only because I would find the sequence of numbers fun to have/illustrate regardless of whether the adjacent notes added monetary or evidentiary value. For just $2 it's just not worth agonizing about. Now if the radar was a $50 or $100, I'd probably just keep the radar since the adjacent notes would not likely provide me with THAT much fun. Just MHO.
+1 Be careful where/how you are influenced by sources of info on collecting. I remember when I first heard the term "bookend" & saw a few sellers try to get premiums for these in 2005. Most dealers admitted they didn't expect more than FV for them. It really hasn't changed much in 19 years. +1 (exactly! Consecutive serial # notes do not necessarily mean UNC). I think it's much more interesting to catch a radar & the matching repeater (if possible). So for the above example: 12344321 finding the 12341234 note would be really cool.
There is a pair of those on eBay right now. Don't remember which seller but they were there yesterday.