Try looking here. You really need to report that to your camera support and not me.
Yes that is normal, your camera uses DIGEST and hence it needs everything sent twice to get the NONCE.
That is a Home Assistant thing, their framework will send new requests each time a new person opens up their UI. 5 people watching = 5 open connections. This binding only makes 1 connection and then distributes it for you to multiple people watching on tablets or phones.
Can not happen unless its a bug in the camera, the binding does not at any time try to change that which is why you need to manually setup the sub stream.
Please take the time to fault find and talk with your camera support FIRST, I am not support and have no connection at all to any camera brand.
I uploaded a new 2.5.x version of the binding for you to try here regarding ONVIF presets:
@Daniel101 this build may help with your Axis camera.