I think
Miriam and
Rebecca sound like sisters. If you have little to no contact with your cousin, I don't think it's a problem. When would
Rebecca 1 and
Rebecca 2 ever see each other?
And no, it doesn't matter what people think, especially if they're people you don't care for. They might think it's weird and wonder if you're honoring
Rebecca 1, but if they ask all you have to say is, "We just really liked the name in and of itself." And if they don't believe you or have a problem with it, oh well. Can't please everybody.
Willoughby wolloughby willina, an elephant sat on Billina.
Willoughby wolloughby wirfak, an elephant sat on Mirfak.