It is known that non-isotrivial fibrations of genus $g>0$ curves over the projective line have a bunch of singular fibers. There are at least three of them.

It is not difficult to prove that an elliptic fibration $X \longrightarrow \mathbb{P}^1$ have at least three singular fibers and at least two of them are not multiple of a smooth curve, provided that it is not isotrivial.

I was wondering if the number of singular fibers that are not multiples of a smooth curve is at least three but I didn't find any proof of that.

Is that true? If an elliptic fibration with an arbitrary number of singular fibers but only two of them are not multiple of a smooth curve, then it is isotrivial?

The surface $X$ is projective and smooth over $\mathbb{C}$