Antique pottery: matching saucer and cup should have exactly the same mark?

[Georg]

Hello

I have seen a pair of pieces, a cup and a saucer, supposedly matching. In fact the design and colour seem the same but under the cup there are some initials and a RD number, while under the saucer there is an anchor and oher word. does this mean that the pieces are not matching?

Thanks

[KC]

Some companies produced pieces under different name at different times during the years.  Some companies produced pieces at different locations.  Very popular patterns were even copied/duplicated by other companies.  Unless we actually see the pieces/marks cannot say what the case is here.