Add-ins for the VBA editor of Office created with VB6 use MSADDNDR.DLL to register the dll not only as ActiveX dll but also as add-in for VBA.
Since MSADDNDR.DLL is no longer shipped with Office 2013 (http://support.microsoft.com/kb/2792179), the setup of the add-in includes MSADDNDR.DLL (version 6.x.y.z) and installs it in the following folders:
So far, so good.
Now, VS 2013 Preview installs MSADDNDR.DLL 12.0.20617.1, so when the setup of the add-in is executed, it doesn't replace that version because it is newer than the old version 6.x.y.z. However, the setup fails when trying to register the add-in dll with regsvr32.exe or similar (error code 0x5).
I guess this is because (using Depends.exe):
MSADDNDR.DLL 12.0.20617.1 only provides two functions:
while MSADDNDR.DLL 6.x.y.z provided also: