MGM movies and the lion

Just popped an MGM film into the DVD player, and got the lion before it started. The lion roared twice, and I recall the lion roaring twice before other MGM films. While I understand that this is easy enough to film once, and repeat in a number of films, my question is:

How did they get the lion to roar twice?

Did they tweak his tail? Did they offer treats? Or did they just repeat the first roar?

There have been sewveral MGM lions. And there have been several websites about them. The easiest to find is the Wikipedia one:

At least one of the lions was trained to growl on command.

For A Night at the Opera, the Marx brothers came on after the Lion and growled:

Here's a compilation of lions:

Related: the MTM kitten and its variants.

The first several lions look either really confused or really high. I didn’t see it mentioned in the articles but was the intention always for the lion to roar or was the first roarer a happy accident? I love lions!

I love the second *Newhart *one, with Bob blandly saying “Meow.”

And don’t forget this one

Missing the great ‘Mimsie on life support’ from the last ep. of St Elsewhere, it seems!