Yes! You can connect the Kinsa app with as many Kinsa thermometers as you want. For example, if you have both a QuickCare wireless stick thermometer and a Kinsa Smart Ear thermometer.
After each thermometer has been set up with your Kinsa app, readings from both thermometers will appear in the app ready for you to assign to the correct profile.
Note: While the Kinsa app on your mobile device can connect with more than one thermometer, each Kinsa thermometer can only connect with one mobile device at a time. If attempts are made to connect one Kinsa thermometer with more than one mobile device, it can get into a state where it won't send readings to either device. In that case, follow this guide to fix the issue.