sorry i was not clear. I took your solution from http://kalx.net/xll/.
The name of the visual studio solution is xlladdins.
It has 4 projects under it (example,test, utility and xll).
I added one more of my own called project1 (by right clicking on xlladdins and then addin new project ) and added code to it and that worked fine.
Now I tried adding project2 following the same method (by right clicking on xlladdins and then addin new project) and added code.
What I observed is if i make project1 as startup project then i see functions of project1 and similar things for project2 (I am in the debug mode when i am experimenting this).
Now are are suggesting to individually load two projects ?