With the HDI unit, if you can run the Down Scan without the 83/200 kHz 2D operating, then you won't get cross-talk.
If you ;can't turn off the 83/200, then you will get cross-talk.
Another option is try operating 83 kHz on one and 200 kHz on the other for 2D sonar.
WIth Hummibird units, both of those frequencies broadcast all the time no matter what the frequency setting is.