Ingegnoli is indeterminate and your one plant is fine since tomato blossoms are self fertile almost all the time because they have both male and female sexual parts. So no ther tomato plant is needed for pollenization.

Carolyn

... and if you want to be addicted to tomatoes, find a copy (buy one, support our favorite tomato lady) of 100 Heirloom Tomatoes for the American Garden

Bets

Here is a link that might be useful: 100 Heirloom Tomatoes for the American Garden

That looks like an interesting tomato. Somehow the Italian varieties catch my imagination....

I've linked the page on your variety at Tatania's TomatoBase, where it's known as Ingegnoli Gigante Liscio or Gigante Liscio (Ingegnoli is apparently an Italian seed company).

Here is a link that might be useful: http://tatianastomatobase.com/wiki/Ingegnoli_Gigante_Liscio