Can we convert the Addon from 32bit to 64bit

Hi experts,

I am currently using 8.81 PL07.

I have developed the addon in 32bit .

Now we are upgrading to 9.1 PL05. when i try to register the addon, i am getting the following error

"The new or same version of Addon is already registered"

what would be the reason ?

thanks in advance,

Dwaraka