Clip to attach two strollers together????

[Olipop]

I know I have seen one of these...I'm sure I didn't dream it! I can't find one on the web. Has anyone else heard of this or shall I just slink away and patent it quickly!
I thought it would be great to have for the occasional time I take a friends LO out as well as my own.

I'm sure I've heard of them too. Was it just for McLaren prams though?

here they are I've heard they're extremely difficult to turn when clipped together but might be ok for a walk in the park that didn't need many tight turns.

here's a pic

They don't have to be the same size or style of pushchair - my friend uses them to clip a pushchair and lightweight child's wheelchair together

ah thank you so much!! I was starting to wonder if I was imagining things!!!! I just thought that it'd be ideal for very occasional use. Good old mumsnet!!! I'll go look at the links now.