Profile copy is not compatible with fields that implement #element_validate

Problem/Motivation

1. We have a shipping and a billing customer profile to fill out on checkout.
2. Billing profile has the "copy from shipping" checkbox checked by default.
3. Shipping profile has fields with #elment_validate callbacks.

In this case the #element_validate callbacks run twice: once for the shipping profile and once or the billing profile. This results in two identical form validation error messages, although the second form is hidden (by #access=FALSE).

Original issue

Hello,

I'm looking for advice on the use case below.
In shipping and billing customer information, instead of the name within the address field, we use a name field, as provided by Name module. This provides us a lot more options to the name field (salutation, and others).
The same name field is added to both shipping and billing information.
We set the shipping address first, and billing address has Enable profile copying on this checkout paneoption checked, and copy from set to shipping.
On the checkout form, My Billing information is the same as my Shipping information. is checked by default, now, when I submit the form, although copy is checked, I get a validation error Name is required..

The reason is probably that Name module checks the emptiness of a field at the "element_validate" level, whereas commerce_customer module handles "shipping > billing copy" later, at the form validate level.

Now I've tried many things, such as implementing hook_element_info_alter() to unshift my own custom element validate that will be able to call form_set_value() when necessary, before name_element_validate() is actually called, but even this does not work.

Any suggestion?

Thank you in advance,
David