values are same
not-type-related is not duality problemIn fact, the only problem in duality is that there's a lot of not-type-related stuff that makes people less compatible.
The example problem of duality may appear if 2 need to do the work, where one can't (or not supposed) do all related to his strong functions and hence part of such work lays on weak functions of other. Such people may have friendly relations and such await it will be similarly good to work together, but it's not obligate. Imagine ESE and LII in small restaurant business. It will be nice if ESE will cook, while LII will get paper work (accountant, delivery, etc). But place that LII on kitchen and problems may appear.