Beads of Nepal origin have good effect on our mind and psychology. All beads are having good effect and different type of effect on our mind and psychology.
Wearing different beads together is definitely acceptable as it will have no negative effect on the wearer.
While wearing 1 mukhi kaju dana rudraksha, which are actually not from Nepal but from India, care should be taken.
Other beads which are from Nepal, are safe to be worn together with other mukhi beads.
While wearing rudraksha, we can choose rudraksha based on planetary requirement or from the bead property selection.
The science or calculation used for selection of rudraksha can be astrological or numerology based. Rudraksha should be worn continuously irrespective of dasha. Choose rudraksha based on jataka overall - birth chart.
After few years, we can change few beads and wear new beads if we feel we do not feel the power that much. But remember we can recharge the power of rudraksha beads by chanting shiva panchakshari mantra.