Joseph Limb
I had the same error message mentioned and found that there was an "advanced tab" in the top right corner of the XLN Online installer. I simply went there and was able to change the directory folders so the 32-bit and 64-bit versions were no longer the same. 

The only thing I would add is make sure you click apply after defining the paths so they get set. I missed that the first time and got the same path error then it closed.

Guitarpima
Where is the path that they are both installed?
 
If they are both in C:\program files (x86)\cakewalk\VST plug ins, then move the one that has x64 in the name and move it to C:\program files\cakewalk\VST plug ins. If it's the other way around then do the opposite.

This worked for me! Thanks! In the installer I chose a new path for the 64-bit. C:\program files (x86)\cakewalk\vstplugins. Also had to direct Sonar to this file path in the utilities/Cakewalk Plugin manager... 

YouDontHasToCallMeJohnson
Do you have a barrel and proper scraping tools?
 
I am now resigned to await the AD support dudes response.

Here is what Addictive Drums tech support told me to do, if you can get this far:
 
Thanks for getting in touch. Sorry to hear about this error. Here are some steps you can take to fix this:
 
 1. Search your computer for "Addictive Drums 2.dll" (no quotes) and delete all files with that name.
 
2. Run the XLN Online Installer and let it repair your installation. This will ensure that only the correct plug-in file is left on your computer.
 
3. Go to the Advanced page in the Online Installer. That page will tell you where the 32-bit and 64-bit Addictive Drums plug-in DLLs are installed. If you're running your host in 32-bit mode, then you want to use the 32-bit plug-in file and vice versa.
 
The next step is to check the preferences in your host. The option is usually named "Paths", "VST paths" or "Plug-in paths". In those preferences, add the path to the correct plug-in and then hit the Rescan button. After that, try loading Addictive Drums again. 
 
Hope this helps!
 

XLNAudio support is pretty good, just not the fastest.
 
1) Assuming you can get to it, click on the Advanced button

 
2) In Advanced Options change the VST32 and VST64 folder settings. 

 
if you can't do the above or just feel comfortable with a little direct manipulation...

• open folder: 
  C:\ProgramData\XLN Audio\XLN Online Installer\App
• Edit the following file (make a backup first)
  config.txt
  Note: even though the file is in ProgramData the file requires elevation to modify.
  Easiest way to deal with this to copy to desktop, modify copy, then copy back overwriting orig.
  You'll still have to elevate to overwrite original.
• Be careful not to screw up formatting (placement of 2 comma and how quotes are used).
  vst,"vst64bit_path"vst_86,"vst32bit_path"

PS - If you're not doing it already separate your 32 & 64 bit VSTs into different folders.  Lots of vendors use the same files names for both sets of plug-ins.

I had the same problem.
 
To fix this I just clicked on Advanced button and then clicked on 32 bit and selected the path C:\program files (x86)\cakewalk\VST plug ins.  That allowed me to install the software so that the 32 bit went to (C:\program files (x86)\cakewalk\VST plug ins,) and the 64 bit went to C:\program files\cakewalk\VST plug ins.  
 
Resolved.

thanks go to TheSteven, one couldn't have explained it in a more and easier undewrstandable way.
RESOLVED; MADE ME A WEEKEND