Yes check with your DMV. My state (Michigan) does allow double towing in some instances (length restrictions apply - and there may be route restrictions as well), but I think you need to get a certification on your driver's license to do so.
I get the idea it's allowed, but not all that encouraged to do so.
And you may have to spend more on insurance as the risk factor for an accident may increase.
So even states that do allow double towing may have certain additional requirements.
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