those I've looked at in the original registers (mainly German but also Andreas + Jurby + a couple more) had the two witnesses usually non-family in the 50 years post act that required witnesses be named (and quite usual the parish clerk was one), maybe this was a hangover from witnessing a will which required non-beneficeries thus implying non-family - towards end of 18th and early 19th family members (brothers etc) started to sign.
There were only ever 2 witnesses - a very very few had no witnesses (suspect clergyman forgot to enter them) I never ever saw more than 2. I have seen the bride sign both names before.