I uploaded 4 images, which show the bug.

Image 1 (Step1.png): shows that there are dispensers, which all have a bucket of water inside.

Image 2: (Step2.png) shows that I activated the dispensers, which leads to the one in the middle dispensing the water, which is correct. But a tick later, the one just below will also dispense its water, which is not correct, since this dispenser isn't activated by any redstone.

Image 3: (Step3.png) shows that the dispenser, that is activated but not supposed to be, also stays triggered (Triggered: true - as you can see on the top right (green color)) even though I turn any redstone off. (The redstone still isn't connected to it, though.)

Image 4: (Step4.png) then shows that even if activate the redstone again, only the dispenser connected will be effected by the redstone and turns on (triggered: true). The one that is bugged (the one below) will not be affected and stay triggered (triggered: true) forever.

Note: That bug also works, if you switch the repeater with redstone dust or so. I tried a lot to fix it myself.

Hope that this is understandable.