Are we allowed to play on multiple Dota accounts?

If a player has more than one Dota account and switches between the two accounts because he has different cosmetic items on each account (e.g. one account to play Kunkka with prestige item, another account to play QOP with other cosmetic items etc), is that allowed?

What if the accounts are of different ranks, so technically he is "smurfing" when he plays on the lower ranked account, but he isn't actually trying to maintain a low rank to stomp noobs, he just happened to calibrate at different ranks on each account.

Is that considered "smurfing"?

Because if that is considered smurfing, then every veteran player who starts a fresh Dota account (which will be of low rank at the start) would be instantly considered a smurf and be at risk of being banned, regardless of their reason for starting a fresh Dota account (and I can think of a few legitimate reasons that have nothing to do with a desire to stomp low-ranked players).

Or is it only considered smurfing if a player INTENTIONALLY obtains a low-ranked account for the purpose of stomping lower ranked players?