multi-column saved reports stomp on each other

[Wm]

Background:
- I have less that 20 saved reports for the book in question
- most of them are multicolumn reports
- they stomp on each other
- OS Win 8.1 though I don't think that is significant
- gnc 2.6.11 but it happened w. previous

I've trundled through bugzilla but can't find this or anything related
to it so either it is me (too many saved multicol reports, perhaps) or
something else, anyway, I'd welcome thoughts.

Before I get going:
on Win (but not *nix)
saved-reports-2.4-backup has CR CR LF line endings
whereas
saved-reports-2.4 has a more conventional CR LF
chances are no-one noticed before.  I did have a look for what I thought
would be my first gnc bugfix but within a few lines I still can't figure
out what the code is doing wrong and this isn't even meant to be
obfuscated :(

Anyway, the more serious issue is that multi-column reports stomp on
each other in a nasty way.

It isn't:
- the size of a report (bytes on disk), tried very big
- it isn't the size of the saved-reports file, tried very big
- it isn't the number of reports in saved-reports, tried lots
- it isn't local memory, the error occurs when plenty free available
  but poss running out of another internal resource ?
- the number of reports in the multi-col, tried lots

Can I reproduce it to order?  Unfortunately not, I've been trying to pin
this down for a few months now and I'm getting closer but not there yet
so let's see if anyone else recognises ...

The reports in your carefully constructed multicolumn report change
spontaneously!

I've written scripts to pull out and reconstruct saved-reports and
become more efficient than I'd like to be at that.

I've got a nice example from the last two days set aside if anyone wants
to look where a multicol report showing a liability over time in two
currencies
===
);;;; Options for embedded report
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;; options for report "ZAR"
(let ((options (gnc:report-template-new-options/report-guid
"faf410e8f8da481fbc09e4763da40bcc" "Liabilities Over Time")))
...
);;;; Options for embedded report
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;; options for report "GBP"
(let ((options (gnc:report-template-new-options/report-guid
"faf410e8f8da481fbc09e4763da40bcc" "Liabilities Over Time")))
===
becomes
===
;;;; Options for embedded report
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;; options for report "Balance Sheet"
(let ((options (gnc:report-template-new-options/report-guid
"c4173ac99b2b448289bf4d11c731af13" "Balance Sheet")))
...
;;;; Options for embedded report
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;; options for report "Wm cc VQ"
(let ((options (gnc:report-template-new-options/report-guid
"2fe3b9833af044abb929a88d5a59620f" "Transaction Report")))
===

where: the "Balance Sheet" and "Wm cc VQ" (a credit card summary) are
from other multicolumn reports.

Help!  I'm not sure what the bug is.

-- 
Wm