Looks like the issue is that the two bills are being treated as separate properties by the app. This is because they have different address formats - one is U607 while the other is 607. A quick fix for this would be to contact customer service and have them update the addresses to match - although of course ideally the app should be able to recognize them as the same place.
I contacted AGL Customer Service by phone on Wednesday evening and was told that they had changed both property addresses to be the same as the postal address on my account (from start of contract) - which was yet a third variation!
I tried the app again on Thursday but there was no change in the display.
I decided to give some more time in case the amendments might take a while to filter through the AGL systems.
I tried again today (Friday) but there was still no change in the app.
I also tried accessing via a browser but the system still showed the different property addresses.
[added
At various times, I used my phone's Settings to clear Cache and Data for the app, force-closed the app and restarted my phone.
None of that helped and, since the problem also occurs with my computer browser, it is not just an app issue.]
Could you try and get this resolved with relevant AGL staff?
I suspect that since the past bills are already associated with the different addresses, they don't retroactively update. Now that both bills match the postal address on your account, the icons on future bills should display correctly for each bill type.