As your first output shows the data is invalid 
The result of the inventory function should only be one value per item plus thresholds if needed for inventory.
But your check is only pulling three different OIDs.
First step is you need to extend your first OID also with a 0. At the moment you get two line in your result because of the missing 0 after ‘11.1.11’ → ‘11.1.11.0’
Now you should only get one line.
If you want to use the Signal State as your service description, i think this is not good if the signal state changes, you need to output the Signal State description as result of your inventory function.
example end of your inventory function
return [(info[0][2], {})]
I would do a change in your service description.
'service_description': "endrun clock",
And then only return an empty value in your inventory. That means if data is present at inventory time then also this check should work.
return [(None, {})]
That’s all