The "Global allocations" or "Allocation history" report will show every possible combination of banner allocations on a given date in the past or future:
Allocation configurations sharing the same banners and probabilities are grouped together. The "Campaign" line describes which campaigns are contributing banners. In this example, "c1, c4 (excluding c2)" has (FIXME: argh, there is an obvious bug in the screenshot) banners from campaigns c1 and c4, and this configuration is specifically "excluding c2" because there is another existing configuration where all three campaigns c1, c2, and c4, contribute banners.
Overlapping campaigns are displayed first, because this is the most likely place to find nasty surprises.