The women, aged 34 and 45, were trampled at the Tarajal 2 border post and rushed to a hospital where they died of their injuries, Mohammed Benaissa of the Northern Observatory of Human Rights told AFP.
Four other women porters were injured in the crush and taken to hospital in the nearby town of Fnid'q, Benaissa said.
Morocco's MAP confirmed the death toll and said that one of the injured was in a critical condition.
Moroccan authorities said they had opened an investigation to "determine the circumstances of the incident".
Thousands of people, mainly women, work as porters transporting goods across the border, sometimes making return trips and carrying up to 70 kilos (155 pounds) on their backs.
Human rights groups have repeatedly denounced their working conditions, describing the women's situation as "degrading and humiliating".
Karima Omar El Ayachi of the Moroccan Association of Human Rights (AMDH) said the porters are "treated like livestock".
Monday's deaths brought to four the number of women porters who have died in similar conditions since the frontier post was opened earlier this year, Benaissa said.
Authorities reopened the crossing in late February and tightened controls on the size and weight of goods that porters can carry each day.
They also set a quota of 4,000 porters permitted to make the run between the two countries.
Unemployment is high in Morocco, where according to the World Bank almost 5.3 million people "live under the threat of falling back into poverty due to their socio-economic conditions".