output array with matching ids

I have 2 collection (customer and subinfo) that pull info from 2 separate database table. both table information are related and i needed to join/merge the info, which i have done.

but unfortunately it's outputting the total number of customers (5) with the merged info and then it is duplicated, outputting a total of 10. see image below.

i need an if statement or something to tell it if $collection->getId() == $subcollection->getEntity_id() then output only the ones with matching ids.

how can i achieve this?