Incremental formula

I am hoping I can get some help on a recent issue I ran into with Excel. I am trying to setup a formula that will perform an equation on 2 columns which is the easy part. My issue is when I try to copy the formula across it isn't updating the proper 2 columns. The data is on a separate worksheet from the rest of the data for formatting reasons. Below is an example of what I want and what I am getting.

Example:

Data Worksheet
1 1 2 2 3 3 4 4

Output Worksheet (Should be) (A1 + B1) (C1+D1)
2 4 6 8

Output Worksheet (What I am getting) (A1 + B1) (B1+C1) (C1+D1)
2 3 4 5 6 7 8

Please let me know if I missed something in the explanation or if something is unclear. Also sorry if this is an easy issue I tried to look around and messed around with offsets but nothing seems to work right.

Thanks for any help on this.