seems the original extension was the old dnnwerk item.

ok no, it's never that easy is it.

With the dnnwerk extension gone, the portals are still created with dual copies of the page manager module.

It appears that the 8.0.3 version of the module has added a second definition named Pages to the one named Tabs, that is included in version 7.0.1 of the extension, as exists on the DNN7.4.2 portal it was upgraded from.

So the result is that the extension has dual identical definitions because the 803 version has a new name for the same controls.

Need to delete the definition named Tabs