depends on the region then. Where I live - neither english nor spanish speaking region - I've never seen
Elisabeth and
Isabel being used on the same person. (And
Isabella is even more different)
To me,
Mary and
Maria or
Alice and
Adelaide look much worse and a lot more similar, in these cases I can understand.
However f.ex. I don't see
James and
Jacob as the "same name", or
John and
Jack or
Nancy and
Anna or
Louis and
Ludwig or
Guillaume and
William ... they already sound to different one from another.