Well, the second K-3 is already bought, and appears to be a rational choice to me. The way these Pentax flagship bodies are built makes a low-use copy also a low risk copy. Especially with a return agreement.
As to the 2nd card slot issue, some never use the two slots, depending on what they shoot and their shooting style. Some in the 35mm film days carried 2 or 3 loaded cameras. The OP says the 2 card slot feature has been important for his wife in her work, so this need will now be enhanced. Her backup has been the K-x (!), so this will be a major advancement as it is. Talk about a difference in controls when using two cameras... and much more! Now there will be uniformity in use and in results.
And, the future is still open to a K-3 III. Acquired ahead of time to become acquainted with the difference in controls, etc. it would remain to be determined how much the special attributes of the K-3 III will mean to her working experience. Perhaps she will notice no difference at all, or very little, or perhaps she will find much to appreciate, and perhaps in the meantime the price will come down yet further.
Last edited by mikesbike; 09-13-2022 at 12:30 PM.