It has been common practice in the whisky industry for more than a century for distilleries to sell barrels of whisky to blenders and independent bottlers as a means of making additional income. In fact, some distilleries exist solely to serve independent bottlers, and do not market any brands themselves.
Distilleries also pass on barrels of whisky to ensure consistency. When blending whisky, they ensure consistency by using barrels with similar flavours. If a particular flavour is notably different, it may be deemed uncharacteristic of the distillery and as such cannot be used in “official” product bottlings. Whiskies bottled by independent bottlers may or may not be labelled with the distillery of origin, but tend not to use the distillery’s trademarks such as logos, fonts and images as they may not have the authorization to do so.