Picard is flagging dupes, but not actually removing them from BAM.
Should look like this:
picard MarkDuplicates \
--REMOVE_DUPLICATES true \
--INPUT /mounts/lovelace/temporary/porter/coreNT_full1/03_sam_sort_coord/1_1_S1.bam \
--OUTPUT /mounts/lovelace/temporary/porter/coreNT_full1/04_picard_dedupe/1_1_S1.bam \
--METRICS_FILE /mounts/lovelace/temporary/porter/coreNT_full1/04_picard_dedupe/input-dedupe-stats.txt