Are you allowed to double major in a BSc?
Nope.
Double major in computer science and mathematics and statistics (
http://www.unimelb.edu.au/HB/areas/SCOMSCI.html and
http://www.unimelb.edu.au/HB/areas/SMATH.html)
Completion of the following subjects will lead to a major in computer science and a separate major in mathematics and statistics with a specialisation in discrete mathematics. Both Departments have endorsed the following recommend subject sequence.
First year433-171 Introduction to Programming (or advanced version 433-151)
433-172 Algorithmic Problem Solving (or advanced version 433-152)
620-141 Mathematics A (or advanced version 620-121)
620-142 Mathematics B (or advanced version 620-122)
620-143 Applied Mathematics (or advanced version 620-123)
620-131 Scientific Programming and Simulation
Plus two additional subjects
Second year433-252 Software Engineering Principles and Tools
433-253 Algorithms and Data Structures
433-254 Software Design
433-255 Logic and Computation
620-201 Probability
620-222 Linear and Abstract Algebra
620-261 Introduction to Operations Research
620-262 Decision Making
Third year433-303 Artificial Intelligence
433-330 Theory of Computation
433-352 Data on the Web
620-352 Graph Theory
620-353 Discrete Mathematics
620-381 Computational Mathematics
Plus one other 300-level Mathematics and Statistics subject and one other 300-level Computer Science subject. Suggestions include 620-361, 620-351, 620-362, 620-374, 433-380, 433-361.
Maybe it's an exception?