There is no problem here. It is for common sense purposes like having a light fixture with 4 sylvania light bulbs and one general electric bulb of the same wattage for arguments sake. Only time will tell if one brand lasts longer than another. All five bulbs will produce about the same amount of light. One could in theory call it a missmatch I guess. But getting another boch plug from a different production run could be much the same. As for the 1/2 volt difference it is about the same principal as one light bulb rated at 115 volts and another at 120 volts. Manufacturing tollerances eliminate any reality here again for practical purposes. No point in trying to expand upon this really. I even mix old and new plugs when removal of the other older plugs is just too difficult without them being really bad. Never seems to cause the slightest difficulty in apparent general function.