Two prices published at products

Hi,

There is nothing wrong. The user will have access to all the prices his account and his user groups give him access to for the current currency.
Changing that to only take into account the lowest one would require some extra coding in the functions removeUneededPrices and _removePrices of the file administrator/components/com_hikashop/classes/currency.php
Note however that you might want that change, but that doesn't mean that it would be correct for anyone.
Some merchants can use the way it works now to set a base price for all the users, and then additional prices with min quantities for some user groups so that they would automatically benefit from reduced unit prices for bulk purchases for example.

Now maybe you want to take another approach to the situation.
If you don't want to remove the "klant5" user group from this user, because you use it for something else, I would recommend instead to create a discount for that product for that user with the value being the difference between the klant5 user group and the 10465 price and limit the discount to that user only.
That way, he'll get the extra discount on the product.