the max duplicate tags is not used for control sample

[Stéphanie Rialle]

Hi all,

I am using MACS2 2.1.1.20160309 and I have a problem regarding the
filtering of duplicate tags when using the --keep-dup auto option.

The max duplicate tags appears to be 18 in the treatment sample, and 13
in the control sample, but it is "18" and not "13" that it is used for
filtering out redundant tags in control :

INFO @ Tue, 06 Sep 2016 10:34:04: #1 total tags in treatment: 26261582
INFO @ Tue, 06 Sep 2016 10:34:04: #1 calculate max duplicate tags in
single position based on binomial distribution...
INFO @ Tue, 06 Sep 2016 10:34:04: #1 max_dup_tags based on binomial = 18
INFO @ Tue, 06 Sep 2016 10:34:04: #1 filter out redundant tags at the
same location and the same strand by allowing at most 18 tag(s)
INFO @ Tue, 06 Sep 2016 10:34:05: #1 tags after filtering in
treatment: 26237285
INFO @ Tue, 06 Sep 2016 10:34:05: #1 Redundant rate of treatment: 0.00
INFO @ Tue, 06 Sep 2016 10:34:05: #1 total tags in control: 14942170
INFO @ Tue, 06 Sep 2016 10:34:05: #1 for control, calculate max
duplicate tags in single position based on binomial distribution...
INFO @ Tue, 06 Sep 2016 10:34:05: #1 max_dup_tags based on binomial = 13
INFO @ Tue, 06 Sep 2016 10:34:05: #1 filter out redundant tags at the
same location and the same strand by allowing at most 18 tag(s)
INFO @ Tue, 06 Sep 2016 10:34:06: #1 tags after filtering in control:
14546481

Is this behavior normal or is it a bug? In my case, this will allow too
much tags at the same position in the control sample.

Thank you in advance for your help.

Best,

Stéphanie