VST errors reported by Bidule

Each plugin can report info/errors of its own. But Bidule can also show supplemental ones on top of those for each plugins:

Duplicate VST plugin ID found ("a.dll uses the same ID as b.dll : PLUG")
This can suggest a couple of things. Either you have two duplicate plugins in your folder (potentially an older version along with a recent one!) or that two developers were unlucky enough to choose the same UniqueID when they created their plugins. In either case, you will have to sacrifice one or the other and rescan. In the meantime, informing the plugin author would be a great help to the community.
VST Plugin Error ("a.dll caused an error while unloading so it will not be used.")
This means the plugin didn't deallocate properly when Bidule was testing it (leaving leaked objects around). While the plugin might work before being unloaded, we found it was wiser to disallow using this plugin at all, since each time you would delete it from the patchbay, it would have left Bidule in an undesirable state. To be on the safe side, you should remove the plugin from your VSTplugins folder, save your layout, and restart Bidule.
VST Plugin Error ("plugin a.dll by companyX caused an unknown exception and will be set to passthrough")
This error will be reported when using the plugin, it means that the central processing function of the VST plugin caused a fatal error. Most other host would have died by now, but instead of killing Bidule, we set the plugin to passthrough automatically. Mind you, as for critical scanning errors, it is always wiser to save your patch and reload it after a fresh restart of Bidule.
Too common UniqueID used! ("a.dll uses a common id")
"Gain","ADlE", "ADly", or "VxSy" Unique ID has been detected. As previously mentioned, Bidule will refuse to use any of these plugins in order to strictly respect the VST 2.0 standard.