The Washington DC area has a number of large homes and mansions which have been restored and opened for visitors. Sometimes more than one place is given the same descriptive name. Such is the case here. Indeed, Wikipedia lists at least 15 towns and locations in the US with the name “Montpelier”!
Montpelier is perhaps best known as President James Madison’s plantation house located in Montpelier Station, VA. http://www.montpelier.org/ Madison’s Montpelier’s history began with Madison’s grandfather in the 1720s, and today’s the Montpelier mansion was built in the 1820s for James and Dolley Madison.
Montpelier Mansion in Laurel MD (http://www.pgparks.com/places/eleganthistoric/montpelier_intro.html) was completed in 1783 for Thomas Snowden. Although Snowden’s Montpelier predates Madison’s mansion, it appears the name of the Madison property predates the Snowden estate. So it’s not clear who borrowed the name from whom … but certainly the Virginia property is much more elaborate than this one in Maryland.
Unfortunately the mansion wasn’t open while restoration work is completed.