Well, I guess one example of the importance of concurrency in two objects would be if you were, say, building a chair-and you needed all the legs to be concurrent. If one was not, then the chair might topple over, possibly injuring whomever was sitting on it.
Another example would be if you were duplicating a stuffed animal you sewed so you can sell it. If the stuffed animal was not concurrent to the previous one, then the customer would be dissatisfied.
I hope this helped :)
