Given the fact that there are 12 signs of the zodiac, and considering the possibility that both individuals could have all their houses in the exact same sign, it becomes a matter of chance and alignment of multiple astrological factors.
Statistically speaking, the probability of two people having all twelve houses in the same sign is relatively low, as it depends on the alignment of multiple planetary positions at the time of birth, including the Sun, Moon, and Ascendant.
In most cases, people will have a mix of houses in different signs, with some houses in common with another person, but it is rare for all houses to be in the same sign.
However, it is worth noting that certain life events and external factors, such as relocation or significant changes in lifestyle, can also affect the way house cusps align, leading to the possibility of some houses shifting into different signs over the course of a person's life.
Overall, the likelihood of two individuals sharing the same placement of all twelve houses in the same zodiac sign is considered a relatively rare occurrence in astrology.