On a quick glance, there are no Copplestone "Gangsters" packs with more than 1 overcoated model. Ditto Footsore's "Irish War of Independence" range (an oft neglected source of inter-war armed civvies - Paul Hicks sculpts, too). There are a couple of packs in Pulp Figures'"Gangland Justice" with 3 out of 5 wearing overcoats, likewise one pack in Brigade Games' "Mob Wars". Great Escape Games' "The Chicago Way" gangsters box has 3 overcoated figures out of 7. The pack of Hitmen in Dixon Miniatures' "Gangsters" range has 2 out of 4 in overcoats.
Brigade also has a pack of 5 identical uniformed police in greatcoats.
If you don't like those ratios, your best bet might be to pick through Artizan Design's "Thrilling Tales" range - figures are all available separately.