Dual Extruder - prints extra "block tower"

I don’t know if this is a software (Cura) or hardware (Taz 4) or firmware issue or ?..
I just updated to have a dual head extruder on our Lulzbot Taz 4. I have downloaded a few different dual extruder objects from Thingaverse and then tried printing them. They print okay, but each print also adds a square tower beside the print object. It is the same height and it is made up of alternating layers of from the two print heads. The “tower block” is not visible on Cura.

It seems to be a waste of filament and time …

Any ideas where this “block tower” is coming from and how to stop it from happening?
Thank you.

Of course, after I pose the question … I find an answer. It appears to be a software feature. In Cura it is called “wipe and prime tower”. It is found under the expert config setting. Also seems to be related to perge walls? Or cleaner columns?

Anyway, at least now I know why and where and I can try with and without …I`ll leave the post for others to find.

Nice find! You use the priming tower as your second head will remain heated when not in use. This can lead to dripping, causing air gaps in the hot end when the second extruder is used. The priming tower just gets things flowing so you do not have these gaps in your actual print. You can adjust the size of the priming tower in the expert options.

I have found the ooze shield to be the most helpful option. This will build up a single pass wall the height of your object. This will wipe off the extruders preventing any “hairs” from accumulating on the object.