I have 2 monitors, and the network speed (aka desk band) always displayed on the secondary monitor as well. After I reinstalled Windows 10 22H2 and the latest NetWorx (v7.1.3), it only shows on the primary monitor.
I've already set Windows taskbar to show all buttons on all screens and "never combine".
It appears you're encountering a known compatibility issue due to the changes introduced in NetWorx v7.0.3. Prior to version 7.0.3, NetWorx utilised a desk band component feature. This was a standard way to extend Windows Explorer and embed custom elements in the taskbar, such as network speed.
However, in Windows 11, Microsoft has completely removed the desk band interface, thus destroying the ability to customise the taskbar with third-party elements. Consequently, starting from NetWorx version 7.0.3, we had to re-implement the taskbar functionality in a way that works with Windows 11. As a fortunate consequence, this also made the feature available in the portable build.
However, this change introduced a minor compatibility issue. Only one network speed graph is displayed, even if the taskbar is configured to show the notification area on multiple monitors. At present, if you want the network speed to display on all monitors, the only solution is to downgrade to a NetWorx version below 7.0.3.