These are not a GI Joe knockoff. Action Man is an action figure toy line launched in Britain in 1966 by Palitoy as a licensed copy of Hasbro's G.I. Joe. They had several series of figures and vehicle, before merging with Hasbro and then releasing the 3 3/4" Action Force action figure.
After Palitoy had ceased production in 1985, Hasbro International released G.I. Joe figures in 1986 utilising the Action Force name, but on G.I. Joe-style cards and over the years they changed them into G.I. Joe.