I’ve encountered a few instances where a resolution or associated_filing is duplicated in a filing history.
You can see an example here: https://beta.companieshouse.gov.uk/company/06137240/filing-history
On the fourth item a reference to the same Statement of Capital appears twice. I’ve seen it happen with resolutions as well. But can’t locate an example at the moment.
There are some irregularities in the filing history data, the occasional duplicate. As described in another post, a lot of work goes on behind the scenes to pull together the hierarchical filing history document the API returns. We’re striving for perfection, but we’re not there yet! 
We’re taking another broad look a the filing history, to mop up these issues.
If anything stands out, let us know.
Cheers