Source

File: wp-includes/pomo/translations.php

function merge_originals_with( &$other ) {
			foreach ( $other->entries as $entry ) {
				if ( ! isset( $this->entries[ $entry->key() ] ) ) {
					$this->entries[ $entry->key() ] = $entry;
				} else {
					$this->entries[ $entry->key() ]->merge_with( $entry );
				}
			}
		}