fatal error when activate Paralax slider plugin

first of all : congratulations for this theme! i am so exited for using it !!

i have an issue when i want to activate the needed plugin Paralax slider.

a fatal error is generate at this moment :s

the message is : 

Fatal error: Cannot redeclare layerslider_load_lang() (previously declared in /health-funding.com/httpdocs/wp-content/plugins/LayerSlider/layerslider.php:101) in /health-funding.com/httpdocs/wp-content/plugins/layerslider/layerslider.php on line 102 

thx in advance for ur help !

best regards