Please describe the problem:
The "Add Report" button will accept and save multiple different reports under
the same name.  I am only seeing this problem if the colliding reports were
created during the same session, i.e., they have not yet been saved or written
out to saved-reports-2.0.  When GnuCash restarts, only one of these reports is
available via the Custom menu, although both reports are saved.  

Steps to reproduce:
1. Create a transaction report.
2. Edit the name to be "foo".
3. Create another transaction report, changing some options.
4. Edit the name to be "foo".
5. For each report foo, click the "Add Report" button.
6. Save and restart GnuCash.


Actual results:
Both reports will be added to saved-reports-2.0, both under the name foo.  When
gnucash reloads, it will complain: 

gnucash: [E] "Refusing to add custom report with the same name as an existing
report."
gnucash: [E] "Please edit your saved-reports file and delete the section for: ""foo"

(Incidentally, I just noticed that there seems to be an extra double-quote in
the error message.)

The following is appended to my saved-reports-2.0:

;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;; Options for saved report "foo", based on template "Transaction Report"
(let ()
 (define (options-gen)
  (let ((options (gnc:report-template-new-options/name "Transaction Report")))

; Section: Sorting


; Section: Display


; Section: Accounts


; Section: General

(let ((option (gnc:lookup-option options
                                 "General"
                                 "Report name")))
  ((lambda (option) (if option ((gnc:option-setter option) "foo"))) option))

  options))
 (gnc:define-report
  'version 1
  'name "foo"
  'options-generator options-gen
  'menu-path (list gnc:menuname-custom)
  'renderer (gnc:report-template-renderer/name "Transaction Report")))

;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;; Options for saved report "foo", based on template "Transaction Report"
(let ()
 (define (options-gen)
  (let ((options (gnc:report-template-new-options/name "Transaction Report")))

; Section: Sorting


; Section: Display


; Section: Accounts


; Section: General

(let ((option (gnc:lookup-option options
                                 "General"
                                 "Report name")))
  ((lambda (option) (if option ((gnc:option-setter option) "foo"))) option))

(let ((option (gnc:lookup-option options
                                 "General"
                                 "From")))
  ((lambda (option) (if option ((gnc:option-setter option) '(relative .
start-this-month)))) option))

  options))
 (gnc:define-report
  'version 1
  'name "foo"
  'options-generator options-gen
  'menu-path (list gnc:menuname-custom)
  'renderer (gnc:report-template-renderer/name "Transaction Report")))


Expected results:
The "Add Report" button should decline to add a report if there is already a
report by that name.  It should pop up a dialog asking the user to rename the
report, or try adding it later after editing the name of the colliding report.

Does this happen every time?
Yes.

Other information:
I discovered this when I switched from 1.8 to 1.9.6.  I had several transaction
reports open at the time, and only some of them were saved.  Some of my reports
were lost, and in trying to figure out which ones were lost, I discovered this
bug.  I orignally thought that I lost my old reports when I first used the "Add
Report" button, but I haven't yet been able to reproduce that.  This may be
related, though.