@wenonah32,
Welcome!
I didn't realize Agastache 'Summer Sunset' was available anywhere this year, but I'm happy you found 2 and that they are doing well.
As for the other 2, are they getting full sun? Sometimes plants grow leggy when they aren't getting enough sun and "stretch" their stems to reach the sunlight.
Some Agastache varieties are taller than others. Agastache 'Summer Sunset' height is listed as 14 - 18 inches. The other Agastaches you have might be a taller variety, so it may seem to you that they are leggy.
