Yes, both types are available (though some variations may possibly only work for Mirror subscribers) - see the FAQ (linked from the Gixen home page) which says:
Do you support group bids?
Yes. Group bids can be used for items that do not have end times within 2 minutes of each other. Be careful not to group items too close to each other by end time, or you might win all of them.
In addition there are two more types of groups available only to mirror subscribers: contingency groups and multi-win groups. Contingency groups are opposite of normal groups: the first lost item cancels all the others in the same group. Multi-win groups are like regular groups, but allow you to specify more than one item to win: e.g. you can win 2, 3 or more items before the remaining items in the same groups are canceled.