how its done?

its NOT a deal , but a Q.

if I place 2 different order in DD or DX , will they combine & send me?

Am asking as too much item (more 50 USD) can be problem from customs.

for ex. today I buy some items, next day I buy sometime.

will they combine orders and send me?

any idea.

DX doesn't combine.

DD don't combine too, I'm asked them today.

Neither DD nor DX combines, from personal experience. Both occasionally split orders though.