When a Custom text column is renamed and then duplicated, the duplicated column name does not get the expected Custom text prefix.

Steps to reproduce:

1. Open Data collection -> Hosts
2. Click "Customize table" and check Custom text checkbox
3. Change that column name
4. Duplicate Custom text column

Result:
Prefix not added (will be added only for default "Custom text" column name)

Expected:
The prefix should be added to the duplicated column name regardless of whether the original field name was changed.