I have two spanners from U534 and they are not like the bike spanner. I know the items sold by the suspected seller may be from RFTF and if so there was a job lot of items sold on. Have you tried to remove the rust from them you may find some markings to help identify or clarify further.

Have a look at one of my U534 video clips where I remove the rust from the U534 spanner. [youtu.be]

Thanks