Thank you for contacting Toolset support. Just to make sure we are on the same page, you are trying to do the following:
1. You would like to add 2 custom fields with same name - one in Custom post and another with same in the User profile field?
2. Will it be a normal custom field or repeating field?
This is possible using some custom code, to fill user profile field we need to have following data:
1) Custom field Value
2) User ID
okay please try it out and let us know how it goes. We can provide basic help on the custom code hints and tips.
Alternatively, for more advance help we recommend to contact Toolset recommended service providers to further discuss the custom approach. We have some recommended list of service providers here if you would like to take a look: https://toolset.com/consultant/