Can we clone fields to an existing object in BOFC?

Yes, BOFC can clone fields to a new object or to an existing object

Experience it for yourself

Bulk Object Field Creator (BOFC) is a must-have tool, designed specifically for Salesforce.com Administrators, that simplifies many of the tedious tasks of managing a complex Salesforce environment.

This tool is available on Appexchange and Click on below button to install the
latest version of BOFC

or learn more