Same certificate for multiple parties in Biztalk Server

Question

Hello,

We have defined two parties for one of our partners. Lets say "Party 1" and "Party 2", both belong to the same partner (just different programs).
Partner originally provided two certificate "Cert 1" and "Cert 2" and we setup them for each of the party (Party 1 - Cert 1, and Party 2 - Cert 2). Bu now, he wants to get rid of the "Cert 2" and only use "Cert 1" for "Party 1" and Party 2". But this doesn't seem to be possible. I cannot setup the same certificate for multiple parties as it say that it is a duplicate. Is there any workaround to this situation? Thank you.