When i have more than one selection in race i actually back them all each way but do have more on the one that i favour usually based on form or time that it has run in trials.I also quinella them and now with the any 2 couple them in that.If you read my posts closely you should be able to pick out the horse i favour in a race.
eg in race 2 i have 2 selections but favour the 2 in race 8 i have 2 selections and dont really fancy either so will back them both eachway.
Hope this helps cheers