pt-online-schema-change error with underscore starting FKs

Doing a dry run on an alter table for adding 2 columns without any index, I get this error :

Dry run complete.  `ayt`.`transactions` was not altered.
Error creating new table: DBD::mysql::db do failed: Can't create table `ayt`.`_transactions_new` (errno: 121 "Duplicate key on write or update") [for Statement "CREATE TABLE `ayt`.`_transactions_new` (

Tried pt-duplicate-key-checker, but nothing on this side.

The constraints are similar starting with single or double underscore, and I found many "fixed" bugs on here with similar errors, but I'm using the latest version of pt and it doesn't work with the following constraints :

    CONSTRAINT `__transactions_ibfk_1` FOREIGN KEY (`user_id`) REFERENCES `users` (`id`) ON DELETE SET NULL ON UPDATE SET NULL,
    CONSTRAINT `__transactions_ibfk_2` FOREIGN KEY (`pavement_id`) REFERENCES `pavements` (`id`) ON DELETE SET NULL ON UPDATE SET NULL,
    CONSTRAINT `__transactions_ibfk_3` FOREIGN KEY (`application_id`) REFERENCES `afflictions` (`id`) ON DELETE SET NULL ON UPDATE SET NULL,
    CONSTRAINT `__transactions_ibfk_4` FOREIGN KEY (`cart_id`) REFERENCES `carts` (`id`) ON DELETE SET NULL ON UPDATE SET NULL,
    CONSTRAINT `__transactions_ibfk_5` FOREIGN KEY (`clone_id`) REFERENCES `clones` (`id`) ON DELETE SET NULL ON UPDATE SET NULL,
    CONSTRAINT `__transactions_ibfk_8` FOREIGN KEY (`refill_id`) REFERENCES `refills` (`id`) ON DELETE SET NULL ON UPDATE SET NULL,
    CONSTRAINT `_transactions_ibfk_1` FOREIGN KEY (`intuition_rate_id`) REFERENCES `intuition_rates` (`id`) ON DELETE SET NULL ON UPDATE SET NULL,
    CONSTRAINT `_transactions_ibfk_2` FOREIGN KEY (`intuition_pro_id`) REFERENCES `intuition_pros` (`id`) ON DELETE SET NULL ON UPDATE SET NULL,
    CONSTRAINT `_transactions_ibfk_3` FOREIGN KEY (`can_id`) REFERENCES `cans` (`id`) ON DELETE SET NULL ON UPDATE SET NULL