Delete duplicate entries from a 2 dimensional array in ror

I am trying to loop an array like this…

@mem = []
@tran = Transport.find_all_by_month_and_vehicle(date,vehicle)
tran.each do |t|
  @mem << [Student.find_by_id(t.mem_id), t.transport_date,] if t.mem_type==“Student”
@mem << [Employee.find_by_id(t.mem_id), t.transport_date,] if t.mem_type==“Employee”

And in the view page I am looping it and displaying it like this

@mem.each do |m|
            <td><%= link_to m[0].first_name} %></td>
            <td > <%= m[0].age %></td>
            <td id="date"> m[1] </td>
            <td id="vehicle"> m[2] </td>

But I am getting duplicates entries here…I need to remove duplicate
entries from this… How do I do it?? Kindly help