APPLSYS and APPS have always the same password and should have the same password.
The only certified way to change APPS password is to use FNDCPASS:
FNDCPASS apps/password 0 Y system/password SYSTEM APPLSYS <new-password>
When you run above command, it will automatically change the APPS password to the same as given above.
That is what I observed. I needed for clarification and I got it from you.