I've known several Deborahs, one was a girl I went to elementary school with, one a teenage friend of my sister's, one was the sister of my sister's first husband, one was a woman I used to work with who has passed on now. The first one is about forty-eight now, the second about forty-seven, the third is fifty-four, and the last would be fifty-five is she were alive now. Every single one of them went by Debbie. I don't know any of their middle names.
I've known one Debra, who is forty-four now. She goes by Debbie also.
I really dislike it, though that's due to a bad association with the last Debbie I mentioned, and not anything inherent about the name itself. It's undeniably dated.
I think Deborah and Debra are pronounced the same. It's always sounded that way to me.