Strange frame your bike has

I'm not speaking about the reinforcements added on it.
According to the the engine holder spacers, it's a right corsa frame.
On this picture, we see the fact that it's a "851" generation (foot pegs), but the font of frame is curved and not welded as the other Corsa until 92.
https://www.flickr.com/photos/redmax...57648608150402
First time I see that, It's a mix between 92 and 93 bike.
Do you know if the bike was crashed and the frame changed after 1992 ?
On that pic, the frame is well welded (but I 'm sure he had two bikes, so it could be "the other one").
https://www.flickr.com/photos/redmax...0402/lightbox/
I will check my photos, but I 'm not sure I have others than in your galery.