Copy of DMP doesn't allow to change the "grant number" field

[Falco-KUB]

Please complete the following fields as applicable:

What version of the DMPRoadmap code are you running? (e.g. v2.2.0)
4.0.1

Expected behaviour:
When creating a copy of a DMP, users should be able to change all information on the cover sheet ('Project Details') independently from the original version.

Actual behaviour:
When making changes to the "Grant number / url" field in the copy version, these changes appear in the orginal version as well (and vice versa) - meaning that this field cannot be edited independently in the original DMP and copies thereof.

Steps to reproduce:

• Create new plan.
• Fill out "Grant number / url" field.
• Save plan.
• Create copy of plan.
• Edit "Grant number / url" field.