Sentinel-1 SLC productFirstLineUtcTime gets overwritten during TOPS Split

During Sentinel-1 TOPS Split operation “imageInformation” metadata gets deleted and replaced with the one computed using product.swathTiming metadata. I noticed that some products have different values for productFirstLineUtcTime and first burst’s azimuthTime tags. The difference is usually 1 microsecond. However, productFirstLineUtcTime is being used in several operators including ThermalNoiseRemovalOp. As a result, there is a difference between processed whole datasets and split ones.
An example of one such dataset is S1A_IW_SLC__1SDV_20180815T154813_20180815T154840_023259_028747_4563.

Here is the crude image of difference between metadata values.

Is there a reason why the metadata is being overwritten? And if so, which processed product is the “correct” one: the original, or the split one?