Woocommerce Booking Calendar has the bookings of all languages in the specific date.

Overview of the issue

The WC Bookings Calendar in the backend has in the list all the languages of a specific booking.

Steps for reproducing it.

Create a bookable product
Go to WCML and translate it
Open a new browser (for not being log in as an admin) and make a reservation in the default language for this product
Go to the backend as an admin in WC Bookings > Calendar.
You can see in the list 2 reservation one for each language.
In the Booking List ( Bookings > All Bookings) you can see only one per language

Workaround

This was fixed in WooCommerce Multilingual 3.7-beta3 available form the WPML.org downloads page.

Also, this patch needs to be applied to WooCommerce Bookings 1.7.13.
https://wpml.org/wp-content/uploads/2015/10/0001-Fix-a-bug-for-WCML-Calendar-synchronization.patch_.zip
The fix will be available in the next WooCommerce Bookings version by default.