I wonder if we are dealing with at least two ARS Cenedese here: one responsible for the enamel pieces (which I admit I know absolutely nothing about) in the 60's onwards, and the other reproducing the pieces that most of us know as Cenedese. We know that on Murano a few names go a long way. Think of Toso, Seguso etc.
I did a Google search and found this on "Find Owner Search": "MURANO CENEDESE VETRI ARS CENEDESE MURANO SRL is believed to be currently owned by “CENEDESE AMELIO”. Treatment of materials, treatment of semi-precious stones, articles of stone, metals and glass materials, glass blowing, glass tempering, glass tinting, and gold plating."
There's another listing for a slightly differently named company at a different address: Company Name: ARS CENEDESE MURANO (S.R.L.)
Detail : Glassware, decorative
Address : S. Marco 30124 Venezia (VE)
There was also a blog about a couple's visit to Venice in 2003 when they visited the "Ars Cenedese factory and showrooms on Murano" at the invitation of one of the owners. Two of the pictures show clearly a whole range of scavo pieces. http://www.callzia.com/Family_Friends/It_Venezia/source/670-818-11.html
My conclusion is that we're talking about at least two separate companies, although, as Alex originally suggested, one might have sold the work of the other. I would modify my statement about anything with Ars Cenedese on it being relatively new, to anything that has Ars Murano engraved
upon it it (i.e. the scavo pieces) is relatively new. It could also be that ARS CENEDESE MURANO (S.R.L.) is still selling work by MURANO CENEDESE VETRI ARS CENEDESE MURANO SRL.
My apologies for muddying the waters.
PS One of Nic's referenced pieces is from Designs and Arts, the German seller I mentioned.