This must be a bug and we need to try to reproduce somehow. Has it appeared just recently for the first time? Can you maybe try to investigate if you see more information about multiple conversions in a visitor profile?

Here is how this can be explained:

When visitors convert a Goal, Piwik tries to attribute the conversion to the referrer that brought the visit to the site (more info on how this works ie. first VS last click). Piwik by default, will credit the last non empty referrer that was used by the visitor before he reached the Goal. It may be a referrer that was used several days ago (and stored in first party cookie).

In your case, you have 1 visit from twitter.com and 3 conversions. What happens likely is that two other visits (without referrer) have converted the goal. These two visitors used twitter.com the first time they visited your website. When they convert the goal later, twitter.com will be credited although their current visit (ie. the last one) wasn't referred by twitter.

I suppose to make this clear to everyone we could:

• when a conversion rate is > 100% in any report, display a new report footer note that explains how it is possible to have conversion rates > 100%

Thanks for the clarification.