I'm not sure exactly what you mean by "insert panes". I will assume you are referring to Plugin UIs?
If so, and if they are Logic's own plugins, just open as many as you want by double clicking on them in the mixer. If they are Audio Units, in principle the same applies, with one caveat. If you are running Logic in 64 bit mode, 64 bit Audio Units will be treated normally, you can open as many UIs as you like (or have screen space for). If however, you use 32 bit AUs in Logic in 64 bit mode, they run in the 32 bit Audio Unit Bridge, which is actually a seperate App, and which only allows single Plugin UIs to be viewed.
If this is not what you mean, feel free to elaborate.
In addition to what Mark said above:
Be aware of the current Link mode you are using.
Double-click an insert slot to open the Plugin window. Look at the little chain symbol top left. If it is lit, then Link mode is on, and every time you double-click an insert slot, the same window will update to the most recently selected plugin.
Click the chain symbol to switch Link mode off, and then every time you double-click a plugin, a new window will open.