Dynamic NAV and GP on the same desktop

Our company has 2 ERP systems, and will continue to have for a period of Time. They Are NAV2009 (SP1 - Classic Client) and GP10. We have been told by GP Experts that we cannot have the 2 applications on the Same Desktop.

Why?

Has your company had the need for these 2 ERP systems, and do they both play well together? Can I put 2 shortcuts on my system to launch the respective databases/applications?

Thanks,

Alan