Hey Frank,
With co-dominant genetics, a non-visual can not carry the genetics. The het form (conda) will always show the trait. In the case of the condas, the only real defining marker is the white wall on the lateral. That will always be present.

If you look at it like recessive genes, the conda is the heterozygous form and the super conda is the homozygous form. Saying that a non-visual can produce condas is like saying a non-heterozygous of a recessive will produce a visual recessive. It just wont happen unless it is a spontaneous mutation that pops up.

This is simple genetics we are talking about here. In over 7 years of crossing and outcrossing of the morph, there has never been a non-visual conda that produced more condas.