if bride and bridegroom mykad address is from a different district (but same state) still can submit application at the same JPN?

Yes, it's possible. I just found out the answer.

If you stay at District A, submit application to District A.

If your other half stay at District B, submit application to District B.

After notice is out, you can choose to register either at A or B.

Just like during MCO to avoid police catching you, u need to check your IC address belongs to which district. I think you check with Google. If Putrajaya falls under the same district, you can submit to Putrajaya for the 21-day notice.

Depends on where you submitted the form, you have to return to that JPN office to collect back the form after 21 days.

When you book for the ROM date, it can be done at any JPN office within the same state, not necessarily the same district as your IC address.