My 5513 went ro RSC/Dallas with a 1520 and came back with at 1570

[Egret]

Many years ago I bought a 5513 from a very reputable seller. I had the watch inspected for authenticity under the principle of Caveat Emptor, and all check out fine. After a few years I sent the watch to RSC Dallas for service and on their itemized inspection report correctly labelled the movement as 1520. I got the watch back and it looked fantastic and I wore it in good health for several years thereafter.

Recently I took it to have new seals, timing adjustment, etc. to my watchmaker and upon looking at his itemized invoice listed the movement as a 1570. Wanting to impress him with my inside baseball knowledge I told him he incorrectly labelled my movement as a 1570 when it was actually a 1520, and only the 5512 had the 1570 movement.

He looked perplexed and opened the case and sure enough the movement inside said 1570.

I was dumbfounded because I knew for a fact when I bought the watch it said 1520. My watchmakers response was that sometimes a RSC might find it expeditious to simply install another movement they have that is running perfectly, rather than spend hours to disassemble and repair a similar movement.

Not that I am interested in selling the watch, but just for my knowledge: does the fact that my 5513 has a 1570 movement in it lessen it's value or "correctness' in the vintage world? In any case I feel like RSC/Dallas should have told me they had done this.

On another forum one of the regs said RSC would never do this but it the only possibility.

Thanks.