This is entirely normal. Uncalibrated monitors really work like this, no two monitor being alike. In fact even if you calibrate them they will slowly drift appart over time. So calibration is something you need to do periodically, with a hardware calibrator (no software will not do).
RGB color values are devoid of meaning without the knowledge of that their profiles are (measurement of what the device shows). Preferably multi monitors should be calibrated to the same profile. Best would be to chose a standard that your monitor can safely attain.
Welcome to the wonderful world of accurate color. Where even the room wall color affects how you understand the color on your screen.
PS: The lesson to learn here is that if you choose colors for web, dont waste too much time on the exact hue, as most monitors are sub par, and not calibrated. So one can not expect others to see the exact same color.