combined shipping broken?

Aladine

Had 2 small orders from same buyer within half an hour, both with same shipping method and not yet set to processed or processing. Although my settings allow combined shipping with a small combining fee, the 2nd order got the full shipping fee again. First time that this arrives, worked fine before. Anyone else with the same problem?

minithingsforlife

I believe it is a choice for the buyer to combine shipping. They have to tick a box.