Instruction: Answer the given question by extracting information from the supporting document.

Input:
Question: Can you use multiples of this unit in the same house, such as two receivers and four remotes? I'm guessing by powering things up in the right order?
Document: I'm using this to monitor two frigs out in the garage that I'm using to store flower bulbs. One frig is on to maintain 40F the other is off to maintain 50F. This is in Florida. I tried with the receiver in the house but it was right on the edge of reception. about 80 feet to garage. So the transmitter is in the frig inside metal garage and it would lose signal so I had to move the receiver to the garage wall using the magnets just stuck it on the wall.
So I followed the user's manual instructions and inserted batteries in the main unit, sensor #1, then sensor #2 in the order. Then I succeeded in having the main unit display temperatures.The thermometer has been in use for our two freezers for less than a day, but it seems more than okay. The suction cup is useless as one of our freezer's internal walls are textured and even the other freezer's smooth internal walls wouldn't hold the suction cup for long.
Only one of the two digital thermometers worked. Not very good quality! I was dri-aging beef so I needed a thermommeter right away. Now I'm stuck with it.
Read everything. I give a good review at the end. Meanwhile...BEWARE. I have no use for the AAA lithium batteries bought because of misleading "bought together" description. The two sensors both need a couple of *AA* *lithium* batteries for reliability in freezer. Total of four AA lithium. Sensors do not use AAA lithium batteries shown in the Frequently Bought Together illustration and description.
First unit I received was defective, it would not read the remotes no matter what I did.So I ordered a replacement, and that unit is working great. The remotes synched within a few seconds of being powered up. I have it in two freezers, using the AA Lithium batteries (not AAA as the description says). The furthest freezer is about 20 feet away and it is transmitting normally.The alarm volume I have not checked (yet).
I bought mine for an RV fridge. My first one didn't work when it arrived. My second one lasted four years until one of the senders went out. The manual has an 800 number where I suppose I could order a replacement sender if my tolerance for being on hold exceeded 10 minutes. No help on the website. It's a great idea, I'll just be waiting until someone builds a better one.
The main unit never recognised the remotes. It said that sometimes it takes several minutes, so I left them on my desk and waited a day. The remotes' red lights flashed, but the main unit still showed nothing but dashes. Tried new batteries, let them sit for two days and still nothing. Had to send them back and they don't refund the shipping fee, so I ate the shipping. I want to try another set, but don't want to eat a shipping fee AGAIN.
Since the freezer is in the garage and it was in the evening, I am sure it would have been open all night before I would have noticed it. The alarm volume is decent for inside the house, but may be a little weak to hear if it were located in the garage, which is why I only gave four stars to my review.I have the receiver located in my laundry room which is between my garage and the kitchen.
Now, I'm not so sure. The unit came with two transmitters, so I'm going to try the second one, but I'm not expecting too much.So, it worked great when it was working, which didn't last all that long.
I originally ordered this back in April. So almost 4 months to get this thing working. I'm a little miffed it's brand new and they already had to repair it once. It seems it should have been replaced.So my advice, if you order this and it doesn't work immediately, return it to amazon, or order it about 4 months before you need them.
Answer: Yes!  I have two of these.  One set monitors my fridge and freezer in the kitchen.  The second set monitors my two freezers in the garage.  I have both receivers magnetized to my fridge.  All four sensors work perfectly.  I attached labels to the receivers to remind me which display is monitoring which appliance.Which sensor is monitored by which receiver is controlled by battery insertion order.  When you put batteries in a receiver and sensor, they synch up and lock onto each other.  Just put the batteries into each sensor one at a time, pausing until you see readings on the receiver for each one.  If you put them all in quickly, you won't easily know which sensor is being displayed where.