Mixing RCA jacks & plugs from different manufacturers or product lines is totally acceptable provided they conform to RCA plug/jack size standards which the vast majority do.
I actually prefer this, as I find that using similar connectors creates a fairly subtle but obvious coloration on the sound. Once you have isolated the colorations introduced by the connectors you can select 2 contrasting ones so that they will cancel against each other leaving you with pure sine waves and perfect squares. The observant reader will also note that by carefully selecting RCA connectors certain colorations from the source, preamp, or amp as the case may be can be reduced or in very good quality gear the colorations can be eliminated.