Voskcoin minidoge fan speed higher than standard version

Hello, I have 2 standard minidoges and 1 voskoin version and found that for the same hashrate and tempreature (186mh/s and 77C), the 2 fan speed of the 2 standard ones sits at around 1500 RPM while the voskcoin at 1900. Is this something to worry about? Did anyone experiment the same issue?