I believe this was the original idea for Thunderball, but with the actors from rival spy franchises as the other agents receiving the same mission
the only citation I can find is TVTropes, which is probably not completely reliable, but this is what they say:
The scene where Bond arrives for his mission briefing with the other 00 agents was originally going to have cameos from the stars of other spy shows and films - Patrick Macnee as John Steed, Roger Moore as Simon Templar, Michael Caine as Harry Palmer, Robert Vaughn and David McCallum as Napoleon Solo and Illya Kuryakin, James Coburn as Derek Flint, Robert Culp and Bill Cosby as Kelly Robinson and Alexander "Scotty" Scott etc. Due to budgetary and logistics concerns, this was scrapped.
any truth to this? given all the evolutionary stages of Thunderball, anything is possible, but this list of names is pretty contemporary to the film's release.