The city’s Rent Guidelines board voted Monday evening to extend the rent freeze on one-year leases for rent-stabilized apartments, in a repeat of last year’s vote. The board also called for a 2 percent increase for two-year leases. Real estate investors have argued that a rent freeze puts a damper on the city’s multifamily investment sales market, as there over 1 million rent-stabilized apartments in the city — nearly half of the city’s rental stock.