Double numbering orders for one order

Apparently, two _oton_number_ordernumber are assigned to the same order...

Plugins installed by both bug reporters:

Contact Form 7: por Takayuki Miyoshi – 4.9
Regenerate Thumbnails: por Alex Mills (Viper007Bond) – 3.0.1
WooCommerce Basic Ordernumbers: por Open Tools – 1.4.3 – Not tested with the active version of WooCommerce
WooSidebars: por WooThemes – 1.4.3
Yoast SEO: por Team Yoast – 6.0
YITH WooCommerce Wishlist: por YITHEMES – 2.1.2 – Not tested with the active version of WooCommerce