I also have the big sister -- the Rival Smart-Pot Slow Cooker:
Rival SCVP609-SS 6-Quart Programmable Slow Cooking Crock Pot Cooker, Stainless Steel
Rival has a habit of making slow cookers that aren't all that slow -- check the Amazon reviews and they are consistent in letting you know these appliances (Rival's, that is) cook at too high of a temperature no matter what the setting. That means your food is done, and sometimes overdone, long before it should be. Grrrrr.
Rival has separated its appliance web sites -- Crock Pots are on their own separate site. Lo and behold, check on cooking tips for their crock pots and you get the following information under "Hints & Tips":
What's the difference between "Low" and "High" cooking?
Both High and Low stabilize at the same temperature, it is just a matter of how long it takes to reach the simmer point. Once food reaches the simmer point, total cook time is dependent on cut and weight of meat to reach the point of maximum flavor and texture potential. (Most dishes can be prepared on either High or Low.)
What are the typical cook times for Crock-Pot® slow cookers?
Typical cook time for Crock-Pot® slow cookers to reach simmer point (209°F):
Low: 7-8 to reach the simmer point
High: 3-4 hours to reach the simmer point
I can attest to the fact that Rival's slow cookers definitely cook way above 209 degrees! If you see boiling food or liquid, the temp is 232 degrees. Think about it -- that means you're really not slow cooking, you're boiling or stewing and you might disappointed with the end results. With that said, I like this smaller duo version because its capacity in each crock is 2.5 quarts, perfect for the smaller family and very handy to cook a main dish plus a side dish or dessert. Note this is not "programmable" in any sense other than High, Low and Warm settings for each pot. You'll have to watch the clock yourself, but considering the fact that everything cooks faster than you expect, I guess that's pretty much a given.
There are some dishes that work well in the Rival brand of slow cookers and some that turn out to be disasters. You'll probably be able to find out for yourself but in general, stews, soups, sauces, any kind of recipe that calls for long stove top or oven cooking will do well in the Rival -- but it will be ready a few hours sooner than you might think. Vegetables definitely need a much shorter cooking time so I add them about two hours before the end of my estimated meal completion. I've even cooked an apple crisp in the Duo and it turned out well.
To sum up, this Duo is handy for smaller recipes or for two dishes, but the Rivals cook too quickly, so keep that in mind. I gave it 3 stars because I now understand to cook all recipes for a shorter time and the device is very convenient for two smaller recipes at once.
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Crockpot SCRBC500-BS Duo Slow-Cooker ServerProduct Description: Ideal for holiday entertaining, buffet-style dinner parties, or other social occasions, this double slow-cooker server features two 2-1/2-quart pots for cooking up anything from vegetarian chili, lentil soup, and beef stew to tuna-noodle casserole, chicken curry, and more. Two separate control knobs make it easy to independently adjust the heat from low to high or warm temperature settings for each pot. The unit's round-shaped, stoneware cooking pots can be used to cook and serve a main dish in one and a side dish in the other, can be removed from their heating base for use as serving dishes at the dining-room table, or can be used to store leftovers, once cooled down, in the refrigerator for later, all of which means less dirty pots and pans filling the sink at the end of the day. Two serving spoons and matching glass lids with stay-cool knobs come included. Other highlights include individual spoon notches, integrated side handles on the removable pots, stay-cool integrated side handles on the heating base, a stainless-steel/black hybrid finish, and four feet that lift the serving unit up, keeping tables or countertop surfaces safe from the heat. The slow-cooker server measures approximately 9 by 25 by 13 inches.
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I've had good success in using this slow-cooker. The features I like: 
