I suppose that's another possibility; that some vendor has mistakenly supplied the wrong part. That style of lamp is very common on old British cars. I don't know offhand which ones used dual-filament holders with red lenses, but I'm sure some of them did.
Whether to keep them that way or replace them with the proper single-filament lamps is up to you. As Andy notes, I deliberately installed dual filament lamps on my 59 TR3A, and wired the dimmer filament to the brake lights (so the turn signals could still be seen when the brake lights were on). I'm not sure the result was worth the effort, but the fellow that hit me admitted that he did not have his eyes on the road (or me), so likely nothing would have helped :frown: