Can I combine this model HX432C18FB2/8 wtih this HX429C17FB2/8 in dual channel?
It is not recommended to mix RAM modules that were not tested to work together, since it is hard to predict the outcome.
Even though half of the time it might just work fine, mixing and matching stick that may have different speed, CAS latency, timings,voltage, etc could cause a motherboard to refuse to work
Even when they appear to be similar, the IC chips might come from different manufactures.
To be sure that RAM will work together you will have to buy RAM kits.
That's why manufacturers and vendors won't provide support for that configuration.