Seems I missed the tag end of this discussion. Just want to throw a few final ideas out. 1.) Dating the label to the late 1960's doesn't do anything but put a maximum (i.e. end date) on it. It may have acquired a new label for a number of reasons. The disc itself could be older than the label, although I doubt that it is. 2.) We are not talking about real or legitimate. There is an object before us and I see no reason to go all Descartes on it. The real question is, what is it? Its 78 rpm speed suggests that the original recording did not originate in the 1960's. Elvis's presence brings it forward to at least the 1950's. The late label suggests that RCA had reason to work with the recording at some point in time consistent with the label design, probably in connection with one or another re-issue package, or possibly that they made the reference recording for someone to use while researching some aspect of Elvis's career. So it is most likely still an acetate dub of something else in RCA's vaults, made to serve as an expendable stand-in for the original, but probably not at the original recording session.
Acetate recordings with utilitarian labels like this one are almost always artifacts of the recording or broadcasting industry. It was certainly never meant to be sold or distributed in this form. Not to make too big a deal of it, but it is also very possibly unique in some respects. It probably is not a lost recording by Elvis Presley, however, unless it represents an otherwise neglected take of an issued recording. (Do such things as takes actually exist anymore? Multi-track tape and mixing boards may have done away with them in most cases.) If RCA did it for themselves, it is probably a sort of test record, made while a session was in progress to allow immediate down-n-dirty playback without disturbing the tape and equipment. The music on it probably exists elsewhere in RCA's vaults in better forms and more probably than not has been issued in a better form as well. Reference recordings are also made off the air by radio stations as part of the regulatory process and so the engineering staff can check the station's performance. If that's what it is, it's just a dub of whatever recording the station was playing at the time.