Yes you must ad de calendar module two times.

		{
			module: "calendar",
			header: "Calendar_1",
			position: "top_left",
			config: {
			calendars: [
					{
			symbol: "calendar-check",
			maximumNumberOfDays: '3',
			maximumEntries:'3',
			url: "her your 1e url"					}
				]
		}},
		{
			module: "calendar",
			header: "Calandar_2",
			position: "top_left",
			config: {
			calendars: [
					{
			symbol: 'calendar-check',
			maximumNumberOfDays: '2',
			maximumEntries:'3',
			url: "and the second url"					}
				]
		}},

Goodluck