Yes, very common. Sometimes it's because the item is defective and passed QC, so the retailer destroys it. Other times, and this reason applies more to luxury brands, is to prevent the item getting into the wrong hands and preventing brand dilution. France recently implemented legislation to prevent this.
To quote The Fashion Law:
"the [fashion] industry, itself, is one of the biggest culprits in terms of the more than €650 million (nearly $710 million) worth of new consumer products that are destroyed or disposed of on an annual basis in France, and the $900 million more worth of unsold items going to landfills, according to Prime minister Édouard Philippe’s office"
and I know this part doesn't specifically target bags, but still..
"In July 2018, Burberry revealed in its 2017/18 annual report that the cost of finished goods physically destroyed in the year was $37.8 million,' that is up from the $35.6 million figure the brand cited for 2017. Swedish fast fashion giant, H&M, had previously made headlines for allegedly burning at least 60 tons of unworn apparel, while Richemont, the parent company to watchmakers Cartier, Piaget, Baume & Mercier, and Vacheron Constantin, among others, made headlines for 'allegedly destroying its expensive, unsold watches.'"
France is home to the fashion industry’s most esteemed names and as of late last month, it is also on the brink of enacting one of the strongest laws when it comes to the handling of unsold garments and accessories. On the heels of revealing that it was working to draft legislation to ban...
www.thefashionlaw.com