I have developed two xlw 4.0 libraries one is HelloWorld1 and the other one is HelloWorld2. They sit in different folders and represent two separate standalone Excel Addins application.
If I load either one of them, it works perfectly. The trouble is if they are loaded into the same Excel Spreadsheet, Excel crashed. It seems that there is a conflict between xlwDotNet-vc80-mt-4_0_0f0.dll sitting in Folder 1 and Folder 2.
My concern is my current project is using XLW 4.0. If another team uses the same technology and works on a different project then the Excel will not be able to load two addins at the same time.