It's an old question, but I believe the answer has to do with a confusing aspect of Construct 2's UI.
In each event row depending on where you click you can select the Condition, the Actions, or the entire Event.
It sound like just the conditions were selected, shift-click to select all of them, and then when pasted, they were all inserted as the Conditions to a new Event.
What you want instead is to click just to the left of the Condition and you will see the entire row (Event) highlighted instead of just the Condition.
Copy and past that and the conditions will stay separated.