duplicate values are being duplicated using Join of 2 columns

[ChrisK51815]

I am trying to join 2 columns (Previous_Value and New_Value) to be able to compare any added or removed values. Here is an example of a data set: 

Previous_Value	New_Value
1221	1221
1221	1221
1221	1221
1223	1221
4556	1223
5997	1223
8481	4556
	5997
	7485

When I do a join from a Record ID, I get the follow output:

Previous_Value	New_Value
1221	1221
1221	1221
1221	1221
1221	1221
1223	1223
1223	1223
4556	4556
5997	5997
Null	7485
8481	Null

But since I am trying to compare what has been removed/added between the 2 columns, I want it to display like this: 

Previous_Value	New_Value
1221	1221
1221	1221
1221	1221
Null	1221
1223	1223
Null	1223
4556	4556
5997	5997
Null	7485
8481	Null

so I can filter for the "Null" values. Any ideas how to make this work?

[apathetichell]

split data stream - new value - tile tool - unique new value.

previous value - tile tool - unique tile tool.

join -> previous value->new value and tile_seq_number to tile_sequence number

union all anchors.

fix your fieldtypes so they are all the same too.

[ChrisK51815]

Thank you. That worked.