Integrity constraint violation

If I add a feed tamper to a field in the feeds importer (I am using Commerce Product processor), then delete the source field in the mapping associated with the tamper (because i misspelled the source name, etc.), then when I try to apply a new feeds tamper to a newly created source mapping field, it will generate this error:

PDOException: SQLSTATE[23000]: Integrity constraint violation: 1062 Duplicate entry '' for key 'PRIMARY': INSERT INTO {feeds_tamper} (id, importer, source, plugin_id, settings, weight, description) VALUES (:db_insert_placeholder_0, :db_insert_placeholder_1, :db_insert_placeholder_2, :db_insert_placeholder_3, :db_insert_placeholder_4, :db_insert_placeholder_5, :db_insert_placeholder_6); Array ( [:db_insert_placeholder_0] => [:db_insert_placeholder_1] => raritan_pdu_importer [:db_insert_placeholder_2] => Price [:db_insert_placeholder_3] => math [:db_insert_placeholder_4] => a:2:{s:9:"operation";s:14:"multiplication";s:5:"value";s:3:"100";} [:db_insert_placeholder_5] => 0 [:db_insert_placeholder_6] => Multiply by 100 to get cents ) in drupal_write_record() (line 6975 of /home/user/website.com/includes/common.inc).

I have to use PHPmyAdmin and delete the tamper record in order to get past the error and be able to add the tamper to the new source field.

Steps to reproduce:
1) Map a source to a target. Click Save. (I used the misspelled Source name PrIce)
2) Click Configure Feeds Tamper
3) Click +add plugin.
4) Select Mathematical Operation, Operation *, Value 100, Click Add
5) Return to mapping, click save
6) Select Remove check box next to recently tampered source, click Save
7) Recreate the Source/target mapping (with correct spelling Price), Click Add, then Save
8) Click Configure Feeds Tamper
9) Click +add plugin.
10) Select Mathematical Operation, Operation *, Value 100, Click Add
11) See above error generated

I think if a source/target is deleted, any associated feed tampers should also be deleted from the database so this error does not occur.