Run several instances of Web Proxy Checker

To run 2 instances of Web Proxy Checker you need to create 2 folders for each instance (for ex. C:\WPC1 and C:\WPC2)
and copy to these folders files from C:\Program Files\Opt-In Software:

wpc2.exe
libssl\libeay32.dll
libssl\ssleay32.dll

Now you can run 2 instances of proxy checker (wpc2.exe) - first instance from folder C:\WPC1 and second instance from folder C:\WPC2.

The problem here is that by default Web Proxy Checker stores its settings to user's Application Data folder.
That means that all instances of program will share their settings.
To avoid this problem you have to use command line argument -appsettingsdir to specify where to save application settings.

To run first instance use this command:

C:\WPC1\wpc2.exe -appsettingsdir

To run second instance use this command:

C:\WPC2\wpc2.exe -appsettingsdir

The same trick works for most other Opt-In Software applications.