Thanks for reporting this. I took a look at the copy number data for DO11034, indeed, there are some very short segments.
The main reason this happens is that the copy number result submitted to ICGC DCC was analyzed by different ICGC member projects, there was not uniform analysis across different projects. The criteria for calling CNVs are determined by each member.
With this in mind, it would be good to interpret the data with caution. It's more of lower level data, further analysis would be necessary.
Hope this helps, please let us know if you have any further questions.