Sub asset InstanceId will relative to main asset's InstanceID?

I want to use AssetDatabase.CopyAsset to copy my asset. I want to Identify it's sub asset when copy over.
First time I use sub asset name to identify same sub asset in Main Asset.but when we have same sub asset name. I can't identify sub asset just use name.

I wonder if the sub asset's relative instanceid is always same relative to Main Asset?

MyAsset : 1000
sub01: 1001
sub02: 1002
sub02: 1003

Copy-MyAsset:2000
sub01:2001
sub02:2002
sub02:2003

If the sub asset instance id is same relative to main asset I can identify sub02(1003) in MyAsset and sub02(2003) will be the "same" sub asset when make a copy.

thanks.