Yes, all the time. Try playing around with different "normalization settings" in your corresponding field inside the document definition. Here you can choose how numbers should be grouped within a given string, which separators to allow etc. It won't always work and sometimes you can end up introducing "ambiguity" which would require scripting in order to resolve. It can get rather complicated.
What I mean is, if you allow a comma as a separator at the "thousands" position, if this is misread as a decimal, and the actual decimal value is read correctly, you end up with 2 decimal values, from which the system will not be able to decide which is correct. This is where scripting comes in. For instance, you could do a comparison between the unit value as captured vs the value obtained by dividing the line total by the quantity. At this point you could programmatically select the unit value closest to the result obtained from this operation.