At present usually two different questions are distributed in alternate columns, where students writing the same exam sit in a column. This prevents copying side-wise, but cannot do so from one sitting on the front or one behind. Sometime, invigilators sign scripts or get busy with other activities. The situation becomes worse when a single invigilator perform his exam duty. Two persons are assigned in a room, but the presence of only one invigilator physically is not uncommon. In order to maintain proper the quality, avoiding plagiarism in the exam hall is a must.
This can easily be avoided/ minimized by using 4 different question sets in a room, and ensuring that no two students sitting either on front, back or side answer the same question set. In odd no. col. (1, 3, 5..) say a, b, a, b... and in even no. col. (2,4,6.. ) c, d, c, d.. arrangement just takes 2/3 minutes more during dispatching question sets only in the beginning of exam.