Linux , db2 9.5 and db2 9.1

We migrated to db2 9.5 now we want to go back to V 9.1

Drop V9.5 instance and Das
Create instance and Das in V 9.1
Rename the newly created sqllib and restore old sqllib folder which was changed while migration sqllib_v91

My Question is do we have to restore this sqllib_v91 back cause when we create new instance it creates for V9.1 ,

sqllib has information about database manager config, register variable etc, does this step is required, i mean new sqllib is created in V9.1 version and does database has any impact if we don't do that