I bought this laminate flooring @ Home Depot a couple of years ago. Just recently I remove a small knee-wall and needed 2 boxes to blend the area left by the knee wall. I could not find the PH 4577, it was discontinued. I ended up getting a similar Pergo flooring, Presto 04709 and improvised.

The tongue and groove style change so they would not match, however, the two styles were close if you put them together using the grooves on both. When put together the new style was slightly higher, all I did was removed a small amount from the top of the groove until it was level when put together. I then glued the joint together. Since the area I was filling in was only one plank wide this was the only alteration I did. This worked for me.