Canada #239 Coil - Patch?

I found the below coil stamp in some I purchased several months ago (certainly not a very pretty stamp). I am trying to determine exactly what the strip on the reverse side is. There is no tear showing on the front side, so I don't think it was a patch. Also, strip is straight on the inner side and has perfs on the outer side - but, the perfs do not align with the stamp perfs which implies to me that the strip was added after the stamp was printed and perf'ed. I think he disturbance on the rear lower left side is just in the gum, I don't see anything on the front. Any ideas as to why this patch was applied?

I believe it is half of a repair paste-up pair. The patch on the back was used to repair a coil of 50/100 stamps.

S-C, I think you are correct, and if so, that would mean the splice piece was "pre-perf'ed"

I think it is more likely that the splicing tape shifted after the coil sheets were perforated, but BEFORE the sheet was guillotined into coil strips.

Ahhh - duh - yep, that makes perfect sense.