Speedmaster reduced (3511.50) bracelet with Seamaster folding buckle?

Hello all,

I've inherited quite some time ago a speedmaster reduced reverse panda (3511.50) with a steel bracelet.
The metal bracelet seems to be original however on the the folding buckle there's the seamaster logo instead of the speedmaster. I did some research and I didn't find any information about such a combination so I have the feeling that only the top sheetmetal part was replaced with a seamaster one because the actual bracelet seems to be an original speedmaster one. The endlinks are the 811 and I guess the bracelet should be the 1469 but without the proper folding buckle.

Hopefully someone can solve this mysterious combination.