Node Help!!

Does anyone know?  When I import files, such as PDF, some objects will have 1 node that looks like it's a double node.  I cannot scroll over it to select it, you actually have to click on it.  So far they only thing I can do to fix this is to go to each node, click on it, break the node apart, and then weld the 2 nodes back together....This is a long long process if there are alot of pieces to the artwork.   Does anyone know what causes this and how to fix it ?