The "straps" which normally appear on Fish vases were a "happy accident", achieved when the piece was turned after dipping it into the batch to gain the partial casing, to stop it dripping/dragging. This piece is not only large, (therefore heavy) but somehow, this "dripping" has been controlled and done away with, but the "corners" are still lovely and rounded.
Double dipping of this kind is supposed to have begun with Harvey Littleton and his first students. But I think there are some late fifties Czech pieces using the technique and and I believe HL may have been influenced by those. However it is one of the first things that most studio glass artists try out when they are starting to experiment, and it is one of those things people do without being aware that loads of others have been through the same process.
Sam Herman is particularly known for double-dipped forms and after studying with HL brought the technique to the UK, where presumably MH saw it it the RCA and refined it with his own thumbprint. You can easily tell the difference between a Herman piece and a Harris piece. Both developed their styles in different directions.
As to the "straps", these can be controlled, but only if you want to avoid them. Arguably pieces with the "straps" are more interesting than without.
There are two artists who studied with Sam Herman who went on to develop their own double-dipped work. These are Chris Thornton http://www.somelikeithot.fr/
and Chris Comins http://www.chriscomins.com/index.html
See also http://www.zestgallery.com/artists.php?display=4
for Sam Herman's work (see Z44 and Z62 in particular for double-dipped with straps and Z35 and Z36 for double dipped without straps)
*it depends on the angle of the blowing iron when you turn it after dipping. If you dip and flip the iron over you get straps. if you dip and lift out turning the iron at an angel of around 45 degrees the glass runs off and you avoid the straps.
During the seventies Daum made a clear crystal wine glass suite using the double dipped technique, called "tulipe" if I remember correctly, and these had no strap lines. They also made a vase.
While it is a possibility, now that Mdina is well-known and raising better prices, that somebody may be attempting to make replicas of Michael Harris' early pieces, I really don't think this is the case here.
If I didn't know anything about Mike and the Mdina story, and I were only looking at 80's onwards, I would have thought Chris Comins could have made this. I don't know whether he has ever worked or hired space anywhere where there is a coloured pot - like at Bristol Blue Glass. If you look at some of his eighties clear and coloured scent bottles there is definitely a similarity in form but I must emphasize that he developed this style completely unaware of the Mdina history, so far as I know.
I can't find my copy of Mark's book. Does the reference actually show it in cobalt? Presumably it does from the comments above, but if not unless there is a record of MH having made some of these from the famous cobalt pot, I would be inclined to approach Chris Comins if only to rule him out.