Panini - Europa 80 (04) - Red backs

1980
(PAP-49) Europa 80
Panini
262 stickers

I came across these the other day and I don't have them in my database. I've no idea where these Red backed stickers come from, I may have seen others in the past but with my poor eyesight the originals seem black. My wife pointed out that the backs of the stickers were two different colours otherwise I would have been oblivious. 
The checklist for this collection can be found here - Panini - Europa 80.