i think i understand what you are trying to say, but it seems incomplete. i am not an expert, but it is my understanding that every surge protector has a voltage threshold that triggers a response if there is a voltage spike.
if the more sensitive surge protector is first, then yes, the second is essentially a power strip. but, surge protectors eventually lose their ability to protect. by chaining two, if the first one dies, the second will start protecting based on the higher voltage threshold.
if the more sensitive surge protector is second, then the second surge protector will provide the initial protection. if the voltage continues to increase and reaches that unit's threshold, then the first surge protector will start to protect. again, if one dies, you have the protection of the other.
because of this inevitable failure of all surge protectors, i use two surge protectors on all expensive equipment. and for years, i have been attaching surge protectors to my four UPS units. as far as i can tell, they work just fine. i replaced the batteries after about 4 years, but that's normal.