Duplicate results Get-SPSite

Hello,

I have an issue with Get-SPSite which seems to be returning duplicate site instances.

Get-SPWebApplication http://contoso.com | Get-SPSite | ft Url,Id

Url                                     ID
---                                     --
http://contoso.com   1bb3a7b4-a59d-4257-8cf9-d74fab04ff9e
http://contoso.com   1bb3a7b4-a59d-4257-8cf9-d74fab04ff9e
http://contoso.com   1bb3a7b4-a59d-4257-8cf9-d74fab04ff9e

As seen in the example, I perform a Get-SPWebApplication, pipe that into Get-SPSite and format a table displaying the URL and ID of the site. This gives me three exactly equal results, I have no idea why. I can access the site wihout issue, in Central Admin it is listed only once. I thought perhaps it was also displaying deleted sites, but Get-SPDeleteSite returns only one (different) site instance.

So what could be causing these duplicates and how can I fix this?

MCTS Web Application Development, SharePoint enthousiast.