I think you would be better off not using disable/enable groups to make things work. Its not really a good way to program in general compared to making your things work for objects based on correct conditions, the functionality in the group should work so it only happen to a frog if its trapped.
A group is simply a virtual container so to speak for organizing and combining functionality in a more logic way or at least it should only be used as such.
So instead what you should do is to check whether a frog is trapped or not, in the case it is, it shouldn't be able to walk.
This can be done simply by using a boolean variable like "Is Frog trapped" = "True or False" and check for it as one of the conditions in the walk functionality. If you disable a group all functionality in that group will be lost for all objects, besides that you might end up with a lot of new problems if you suddenly enable the group and it then starts to affect all the frogs it shouldn't.
In cases like these, where you make an event that should only trigger one object under a certain circumstance and it triggers two or more and you are unsure why, there are pretty much only two possible causes for that.
1. Your picking is wrong, meaning you haven't made the correct conditions for the event.
2. One or more variables for an object is not correctly set. In your program it could be that for instance, a frog "is Frog trapped" variable is not set to "True" when it collide with a trap.
I would suggest you read this:
How events works - https://www.scirra.com/manual/75/how-events-work
Functions - https://www.scirra.com/manual/149/function