I think they are saying that some aluminum cents were struck and some bronze clad cents were struck. 2 separate events.
Not sure but the way it is worded sounds like those were Bronze clad Aluminum. If it is the other way around then that would explain the Aluminum appearance.
OK so then if any of those were in circulation and/or still might be a magnet would attract them. Interesting. So it's time to start using a magnet on all coins.
As part of the cent change proposals for 1974, in addition to the aluminum cents, a quantity of cents were made of steel, coated with copper. When neither of these proposed changes were authorized by Congress the samples of each type were destroyed. What happened to the aluminum cents has already been discussed here. The steel/copper cent were sent to a foundry in PA to be melted down. At least one of these steel cents has been found and it is possible that others may surface. However, neither the aluminum nor the steel cents are legal to own (notwithstanding the Toven cent) and are subject to confiscation by the Secret Service. http://www.coinfacts.com/small_cents/lincoln_cents/memorial_cents/1974_cent.htm
Several of the 74 bronze clad steel cents were recovered by one of the foundry workers at least one, possibly more were sent to Coin World for examination. I know they had pictures of it and I seem to recall there was more than one in the picture. I do not know the current location of the these cents.