It's a double jigger, the handled form like yours is fairly common from the mid 20th century to present, in various metals and handle materials. Have seen the conjoined MP or PM ITALY mark on quite a few items, they've all been silverplate, some with wear showing a brass base. There would a mark indicating so, if yours were solid silver:
http://www.925-1000.com/Fitalian_marks_01.html" onclick="window.open(this.href);return false;
The "mustard test" indicating "solid silver" is an example of rapidly spread misinformation on the internet; mustard is one of any number of substances (eggs, mayonnaise, onions, wool, latex, oak, etc.) that will, with varying speed, produce tarnish/silver sulfide on both solid silver and silverplate (electroplating deposits a thin layer of fine silver on a base metal).
~Cheryl