Forum:Question about beta gate

I have just been re-watching SG-1 from the begining and something occoured to me mid way through season 3 as Thor's ship takes alpha gate to the bottom of the ocean when it re-enters earths atmosphere. General Hammond orders the immediate un packing of the Beta gate which is used up until it's destruction. However the Point of origin symbol on the beta gate is supposed to be different to the Alpha gate (it is something that the Sam points out in season one in the episode Solitudes when the gate is discovered). All of the material up to the destruction of beta gate it uses the same point of origin symbol as the alpha gate.)

Sorry if someone has been over this already. Any thoughts? Continuity error or plausable exlplination? Seems more continuity to me, surely Sam would have noticed if the PoO sybol on the DHD in antarctica was different from that on the gate right in front of her, ie DHD has Ō and arctic gate has ʌ symbol.