Is it possible for left-join to create duplicate records?

[#1]

Let's say there's a tabled called MAIN which uses a field called ID to reference to other tables.

There are over 5 tables that also contain the field ID.

For each of these 5 tables, I do a left join like this:

LEFT JOIN (MAIN)

LOAD

     TABLEx_ID as ID,

     field1,

     field2,

     field3

RESIDENT TABLEx;

So every time I run a script like that, MAIN keeps getting more fields added.

If MAIN started off with no duplicate records before running any LEFT JOIN scripts,

is it possible that after doing LEFT JOIN a few times,

MAIN can get some duplicate records?

[#2 · Accepted solution]

You get multiple lines for an idea in MAIN as soon as you join a table in which ID is not unique means you have to lines with the same ID in the joined table.

[#3]

During the LEFT JOINs,

The rows where ID is null in MAIN should not duplicate any rows right?

They should just end up with the added columns as blank?

[#4]

What do U do when joining Ledger entries and Item List for example?

How do U join to avoid duplicates when joined?

THX