The rules of sentence formation allow ellipsis. This is possible because the deleted information is understood. However, this can result in ambiguity.
Consider the following examples:
Mark and Victor or Linda will go.
We'll have bacon or ham and eggs.
The old man and woman have left.
It costs four or five hundred dollars.
These are the possible interpretations:
[Mark] and [Victor or Linda] will go.
[Mark and Victor] or [Linda] will go.
We'll have [bacon] or [ham and eggs].
We'll have [bacon or ham] and eggs.
The [old man] and [woman] left.
The old [man and woman] left.
It costs [4] or [500 dollars].
It costs [400 or [500 dollars].
Without ellipsis, the sentences are not ambiguous. For example, no ambiguity occurs in the sentence Mark will go and Victor or Linda will go. Though the sentences with ellipsis are ambiguous, one interpretation is more common than the other.
In the first example, the interpretation [Mark] and [Victor or Linda] is more common because most hearers assume that the choice is between one person or another. With the second example, the most common interpretation is [bacon or ham] and [eggs] because most hearers assume that the meal will include two items. In the third example, the interpretation The old [man and woman] is the most common because most hearers assume that both the man and the woman are old. The interpretation [400 or 500 dollars] is the most probably in the final example because 400 and 500 are much closer in value than 4 and 500.
Ellipsis is very common in sentence formation. However, the uses of ellipsis can create ambiguity. Nevertheless, one interpretation tends to be more common than any other.