I created a table of 30+ columns and when I clicked Save I got #1061 'Duplicate key named xxxxxx'. I am assuming that the duplication is on the next column, but I can't be sure. The only way I can fix this is by re-entering a column name and re-selecting the index to rename it, assuming I have selected the offending column. It would be helpful if after naming an index, the index name was displayed beside the index in the index drop-down list, plus a way of editing/renaming the index name.
Implemented with https://github.com/phpmyadmin/phpmyadmin/commit/06a5e07808fb41918f242aa977b9f3b57fef9f47