Help with a Submariner 5513

Hello everyone, I desperately need the assistance of the experts. I have a Rolex Submariner 5513 which I bought from a good and respectable friend a while ago. I never doubted of the authenticity of the watch, until yesterday when I read a post of another VRF member, regarding a similar watch that he just found out was fake. I immediately ran to check the 3 Submriner 5513 I own, and two of them are perfect, but this one.. Here's what I need to know: in the movement it has the following engravings:

MONTRES ROLEX S.A GENEVA SWISS
TWENTY SIX 26 JEWELS
UNADJUSTED

??? Neither of my other 2 Subs ref 5514 have this engraving. I have been doing a lot of research, but the only conclusive thing I found out was that Manufacture des Montres Rolex SA manufactured movements for Rolex, is this true? Any help will be extremely appreciated, I know my friend is a very respectable person, and I know he would respond to me regarding this issue (even though I bought the watch some time ago), but I don't want to tell him if I'm not sure what I'm talking about. Does anyone have reason to believe it can be fake? Thanks in advance for any assistance, and sorry for the long post.