Learn Italian: Tutte e due le sorelle sono fisicamente identiche.

In Italian, when you use tutti e due (or its feminine form tutte e due) followed by a noun, you must always include the definite article (le in this case). It literally translates to "all and two the sisters", which is a common way Italians express "both sisters".

Why is it Tutte e due instead of the standard Tutti e due?

The word tutti has to agree in gender with the noun it refers to. Since sorelle (sisters) is feminine, tutti changes to its feminine plural form, tutte. The number due (two) stays exactly the same because numbers do not change for gender.

Could I use entrambe instead of tutte e due in this sentence?

Yes! You could say Entrambe le sorelle sono... to mean the exact same thing. Notice that just like tutte e due, the word entrambe must match the feminine gender of sorelle and must also be followed by the definite article (le).

Why does the adjective identiche have an "h" in it?

The singular feminine adjective is identica. To make it plural to match le sorelle, it becomes identiche. You have to add an "h" before the "e" ending to keep the hard "k" sound of the original word. Without the "h", the ending "-ce" would be pronounced with a soft "ch" sound.