Import product works but unused tier prices are not removed

Question

With the import I overwrite existing products. I use the Magento dataflow/batch.
New tiers (price) are added and current tiers are overwritten.
But when an existing tier line is not used it will not remove the line.

As example I have the next tiers:
Qty Price
25 1,84
50 1,70
100 1,60

The import field looks like:
32000=50=1.65|32000=100=1.50

The result is:
Qty Price
25 1,84
50 1,65
100 1,50

But it should be:
Qty Price
50 1,65
100 1,50

Why is the 25 qty not removed during the import?
I'm using Magento 1.6 CE

Answer 1

I finaly figured it out myself.
I needed to set the batchparameter append_tier_prices to false.
I don't know if this a core Magento parameter or if this was implemented by the earlier webdeveloper.