Yes they do. All about traffic management and car park capacity. The grounds are only a few hundred yards apart and when both play at the same time nothing moves!
I have joined one of the Northampton Towns forums and they have commented on, bet the vast majority of them are happy about this ground share.
They seem to think we are a decent group of fans and feel a little sorry for us but its obvious they do not know the whole story. The Cobblers think its only for three years, they think we will be filling there ground each week. suggesting what pubs to go to ect.