'ctracker_info_regip_double' => 'There has already been a registration from this IP-Address. From security reasons only one registration from the same IP address is possible.',
Should be (IMHO ):
'ctracker_info_regip_double' => 'There has already been a registration from this IP-Address. For security reasons only one registration from the same IP address is possible.',
(changed "From" to "For")