I see no reason in your code why the commandbar is created 2x times.
my suggestions for now:
1.) may you have a dead ui element(commandbar, may you call Add before without the temporary:false argument). try load the office application without your addin and see a dead commandbar "EquationToolsNET" still exists. (you can remove this easily in the office application or the NO Developer Toolbox)
2.) make sure your addin is loaded only 1 times, check the registry Office/Word/Addins. May a previous addin version want load here
3.) Use the CommandBars.Find method before Add to make sure no duplicate item is created
4.) teamviewer session to help you directly :)
*Sebastian
my suggestions for now:
1.) may you have a dead ui element(commandbar, may you call Add before without the temporary:false argument). try load the office application without your addin and see a dead commandbar "EquationToolsNET" still exists. (you can remove this easily in the office application or the NO Developer Toolbox)
2.) make sure your addin is loaded only 1 times, check the registry Office/Word/Addins. May a previous addin version want load here
3.) Use the CommandBars.Find method before Add to make sure no duplicate item is created
4.) teamviewer session to help you directly :)
*Sebastian