Fatal error while creating an account

Hello,
I installed the plugin on the latest version of joomla, with le latests versions of both kunena and jomsocial and i get an error message when a user try to create an account :

Fatal error: Cannot redeclare class ReCaptchaResponse in /home/xxxxxx/public_html/plugins/system/easycalccheckplus/easycalccheckplus/recaptchalib.php on line 145

The error message only display when :
1) Recaptcha option is activated on ECC+
2) User try to create their account from Kunena or jomsocial (the error message o not appear when they try to create an account from the member K2/Joomla link).

Can you help me please ?

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