You can create it if you wish to set some configuration settings, like RPC user and password for example on startup.
I think the old wallet contained some old format of addresses, perhaps just some in very early "pubkey" format used in earlier mining; and the migration has converted them over.
You can just ignore them or create new addresses if your receiving in future. Don't think there's an option to delete them.
This is where a browser block explorer comes in handy. (See next post).
Remember a bytecoin transaction can contain many inputs, (and many outputs), so it might not be just one sending address that was used.
Then go into your home ISP router/modem and check one or both UPnP and NAT-PMP are switched on inside that too.
The port should be automatically opened for you.
Don't spent too much time on this. If you can't do it, don't worry about it.
Got v 27 up and running on another computer. You should e able to see it on your machines. Still having problems getting my old hardware to work with v 27 but continue keeping at it.
Don't like enabling UPnP on any windoze machine. Too dangerous.
Checked some older BTC core builds and it did have deletion for receiving address. Don't know when that changed.