Is it permissible to take out a loan to perform Hajj on behalf of the deceased if the borrower has already performed Hajj for himself?

May Allah reward your keenness to honor your father. Taking out a loan to perform Hajj on his behalf is permissible and there is no harm in it, provided it is not associated with anything that would prevent it, such as usury, and you are hopeful of repaying this debt. However, leaving it is preferable. It is better to wait until you are able to perform Hajj on behalf of your father without needing to take out a loan.