Every new field was created twice.

Hi,

I just customized my Products Form and created a number of new fields. But for some reason, every newly created field was populated twice.

An original field  disappeared (used it in the form) and a duplicate of each field sits in 'Unused Fields' section. In addition, it added a word 'Base' to each duplicated field.

Does somebody knows why this happened? (It never happened before with any other forms) and how to delete those fields?

Thank you

Monika