this is from the IRS regulations 1.121-1(b)
(2) Principal residence. In the case of a taxpayer using more than one property as a residence, whether property is used by the taxpayer as the taxpayer's principal residence depends upon all the facts and circumstances. If a taxpayer alternates between 2 properties, using each as a residence for successive periods of time, the property that the taxpayer uses a majority of the time during the year ordinarily will be considered the taxpayer's principal residence. In addition to the taxpayer's use of the property, relevant factors in determining a taxpayer's principal residence, include, but are not limited to -
(i) The taxpayer's place of employment;
(ii) The principal place of abode of the taxpayer's family members;
(iii) The address listed on the taxpayer's federal and state tax returns, driver's license, automobile registration, and voter registration card;
(iv) The taxpayer's mailing address for bills and correspondence;
(v) The location of the taxpayer's banks; and
(vi) The location of religious organizations and recreational clubs with which the taxpayer is affiliated.
so based on the info you provided the rental would be your principal residence. the one you own would be a second home.
and thus the home you own would not qualify for the home sale exclusion.
