Table Merge creates duplicate records

So, I am having the same issue and I just found your post and read it with hope. Although it has been helpful my issue is a little different just a tiny bit.

What I am doing is mergint two tables I am creating with M inside the advance query for one of my tables. In this operation I create two tables by doing a left anti join, that works fine.

I have table A that are all new leases.

I have table B with all terminated leases.

I want a single table C with both, so I need two columns, new lease, terminated lease. All this is fine so far.

I do then a nested join which is a left outer from the new leases to the terminated leases, so im keeping all that is new and just putting a false in those that are not.

The moment i merge is ok, but then when i expand the table is when booom, i get duplicates. The problem i just found is that while im using lease_id as my key to join, there are some that do not have that key because they are not leases, they are owned so it is a different number, and coincidentally those are the duplicated ones.

Any ideas on how to solve it ???