Probably interpolated from Jeremiah 10:12-16 (the only verbal difference is in Jeremiah 10:19, where "Israel" is left out before "the rod of his inheritance"). But may not Jeremiah have quoted himself?
Conceivably, yes; but he would surely not have quoted such a passage here, where it spoils the context. For granting that a point of contact with verse 14 may be found for verses 15, 16 (Jehovah who has sworn has also the power to accomplish), yet the passage on the idols stands quite by itself, and distracts the attention of the reader.