Changing Wh, theoretically shouldn't harm the device as it would only take as much as it needs.  Although, you change it means you are buying something off brand unless Dell sells the same model in 2 different capacities. Return the replacement battery. Buying third party laptop batteries are playing lottery.  
So i bought a replacement battery for my dell computer and then when i put it in the thing charges then doesnt then does and it does that a lot so i just want to see if it was the Wh or something elseBtw it  doesnt do it with the original battery
Is changing battery Wh harm the computer