They'll resemble eachother and will probably look like siblings, but being completely identical is unlikely. One set it twin's children may resemble their mother più while the other's might resemble their father more, o they could evenly resemble their parents but in different ways. They will look alike, yes, but they probably won't be identical.
The odds of them being identical is very very very low. The same odds as having a baby, then later having another baby, identical to the first one. te don;t have any control of which chromosomes are being used.