Me again... ;D
As per the title, planes only reserve runways when landing or taking off. They don't reserve it when taxiing off the runway, removing the need for engineering taxiway solutions.
The left plane is taking off, having been allowed to reserve the runway, despite the right plane taxiing back towards the stop tile (having landing).
(http://i.imgur.com/uZatedQ.png)
It's Tenerife all over again... :(
Try -r7164
Yup, fixed in r7164! Thanks!