The quickest way to create UV sets is while you map UVs. When you map UVs, open the options window, turn on Create New UV Set, and type a name in the UV Set Name box. For example, if you create two planar mappings, one from the top and one from the side, type a new UV set name each time you map.
Alternatively, you can start with an empty UV set and then create UVs.
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