Data_Engine: in some cases SplitRequestTreeByType returns the result twice

#### Description:

As in the title, when there is only one instance of the given type of `IRequest` wrapped in a `ILogicalRequest`, the method returns the output twice. Luckily seems to be nonharmful for the current workflows.

#### Test file:
On [SharePoint](https://burohappold.sharepoint.com/sites/BHoM/02_Current/Forms/AllItems.aspx?FolderCTID=0x0120008122C8891F89054B8ACED0196C70DFC4&id=%2Fsites%2FBHoM%2F02%5FCurrent%2F12%5FScripts%2F01%5FIssue%2FBHoM%2FBHoM%5FEngine%2FData%5FEngine%2F%232412%2DSplitRequestTreeByTypeBug%2Egh&parent=%2Fsites%2FBHoM%2F02%5FCurrent%2F12%5FScripts%2F01%5FIssue%2FBHoM%2FBHoM%5FEngine%2FData%5FEngine).