well straight from IMBRA it states, so it sounds like if you cancel a case that was not approved you are cool .. but this is all just assumption.. you won't know until then.
‘‘(2)(A) Subject to subparagraphs (

and ©, a consular officer
may not approve a petition under paragraph (1) unless the officer
has verified that—
‘‘(i) the petitioner has not, previous to the pending petition,
petitioned under paragraph (1) with respect to two or more
applying aliens; and
H. R. 3402—108
‘‘(ii) if the petitioner has had such a petition previously
approved, 2 years have elapsed since the filing of such previously
approved petition.
‘‘(

The Secretary of Homeland Security may, in the Secretary’s
discretion, waive the limitations in subparagraph (A) if justification
exists for such a waiver. Except in extraordinary circumstances
and subject to subparagraph ©, such a waiver shall not be granted
if the petitioner has a record of violent criminal offenses against
a person or persons.
then later it states
‘‘(4)(A) The Secretary of Homeland Security shall create a database
for the purpose of tracking multiple visa petitions filed for
H. R. 3402—109
fiance´(e)s and spouses under clauses (i) and (ii) of section
101(a)(15)(K). Upon approval of a second visa petition under section
101(a)(15)(K) for a fiance´(e) or spouse filed by the same United
States citizen petitioner, the petitioner shall be notified by the
Secretary that information concerning the petitioner has been
entered into the multiple visa petition tracking database. All subsequent
fiance´(e) or spouse nonimmigrant visa petitions filed by that
petitioner under such section shall be entered in the database.
‘‘(

(i) Once a petitioner has had two fiance´(e) or spousal petitions
approved under clause (i) or (ii) of section 101(a)(15)(K), if
a subsequent petition is filed under such section less than 10
years after the date the first visa petition was filed under such
section, the Secretary of Homeland Security shall notify both the
petitioner and beneficiary of any such subsequent petition about
the number of previously approved fiance´(e) or spousal petitions
listed in the database.