Creating (almost) Duplicate Rows

Hi everyone, I'm migrating some information for a client at the moment. They had everything in Excel files and I'm getting them into SQL Server. There are some differences in the way I am storing data and the way they were storing data.

For each client they stored, they had something like
Rel1 Rel2 Rel3
100 101 102

Now, what I have is a seperate row for each of Rel1, Rel2 and Rel3 so I would have 3 seperate rows with identical information except for Rel1. So I would have:
Rel1
100
101
102

So one way I thought of doing it was inserting a new row specifying that the value for Rel2 should be stored in Rel1 and for the next row that the value for Rel3 should be stored in Rel1.

Now, I am able to do this but SQL Server inserts an extra row will the NULL value in Rel1. Does anyone know why this would be happening? I think what it is doing is finding a NULL value in Rel3 after creating the two extra rows and is inserting that NULL. So I think I need to check for NULLs and not allow it to create a new row if, say, Rel3 is NULL.

Any pointers are gladly welcome. (I know it's complicated )