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that will happen if the database units of the layouts are different. In general you should make sure you're working with a common database unit.
Please check whether this is the case and correct that by saving the layout with a different database unit. It's safer to chose a smaller one, so you should correct the one with the bigger DBU to the smaller DBU.
To avoid rounding issues, you should save to a database unit that is an integer fraction of the current one (for example 0.01 -> 0.001).