The due diligence process is a holistic review of the person and their connections – it is not based upon nationality.
Not in all, but in many situations, any citizenship or residency that is currently held or previously held will be discovered and reviewed equally.
Likewise – in many instances – applicants with multiple citizenships or residencies [of 6 months or more] will need to provide PCCs [Police Criminal Clearances] for each.
However, this situation and the protocols implemented vary from program to program and from country to country, so if this issue is present in your situation, it is best to schedule a free consultation with an expert at Astons.