They might play together, then they might not, it's a crapshoot, even using two sets of the same exact model can be and often is problematic, mixing different brands, timings, sizes, voltages, etc can make it harder...if you do try and have problems give me a shout..and with what you show 2GB sticks and 4GB sticks whether they will or can run in dual channel will depend on the mobo, CPU combo....it's not quite as easy as many will have you believe, but then it's not their money being spent
The forums are full of of people who have taken this 'No problem' advise and come here looking for help, see them every day