JabRef 5.1--2020-04-08--8968ccf
Linux 5.5.15-200.fc31.x86_64 amd64
Java 14

In the preferences/entry table columns I can add custom columns. Jabref does not differentiate whether I add a column booktitle/title vs title/booktitle.

Steps to reproduce the behavior:

1. Open Preferences | Entry Tabel Columns
2. Add booktitle/title in textfield below the list, press "+"
3. Add title/booktitle in textfield below the list, press "+"
4. Close preferences, and see effect on entry table: two identically named columns booktitle/title.