How to make
Prepare the puddings as described on the package. If you have the type of pudding that's prepared without boiling, mix the contents of the packets with cold, sweetened milk and stir. If they do require boiling, pour them in hot, sweetened milk and stir. I recommend the first option.
Dip the biscuits in the cold milk and arrange them in a baking dish. Arrange a row of biscuits, then cocoa pudding, biscuits again, vanilla pudding, then biscuits, cocoa pudding etc.
The last layer needs to be pudding, 1/2 cocoa and 1/2 vanilla. Use a knife or fork to make streaks going both directions, in order to get the colors to blend into one another.
Allow to sit for a bit and then serve.