Druid pelts can naturally spawn with up to 3 different druid skills regardless of rarity, max value is +3.
+druid /summoning skills are prefixes from the same group which roll for magic/rare item- you can have either first or the second one, not both.
So for white or higher rarity you can have up to 3x "1-3 to X skill(Druid only)"
For magic you can also have +1-3 Summoning or +1-2 Sruid skills while for rare it would be +1-2 Summoning or +1-2 Druid skills.