Summary: Is the Samaritan Targum's harmonization of the beginning of Shlach with sefer Devarim an example of Ziyuf?
Post: The sidra of Shelach begins (pesukim with Rashi):
Clearly, there is an issue in that here, Hashem seems to be the initiator of the command, and says to do it for their benefit, while in Devarim, Moshe criticizes the Israelites for making this request. There may be various ways of resolving this, but Rashi, based on Sifrei, explains that they first asked, Moshe consulted with Hashem, and Hashem allowed it, to give them room to err with the spies, so that they would not inherit it.
The relevant pesukim in Devarim (1:20f):
and so on.
The Samaritan Pentateuch just merges the two accounts here:
Thus, they change the first person וָאֹמַר אֲלֵכֶם in pasuk 20 into ויאמר משה לבני ישראל, but then follow the script from Devarim until pasuk 22, and finally, change the first person וַיִּיטַב בְּעֵינַי הַדָּבָר into וייטב הדבר בעיני משה. Then, they pick up the beginning of parashat Shelach just as we have it.
Naturally, the Samaritan Targum follows the same pattern:
It is, after all, simply a translation of the Samaritan Hebrew into Aramaic.
Targumana (Dr. David Golomb) takes note of this,
relating it to the forging and additions of the Samaritans, even as its 'source' is in the Sifrei which is brought in Rashi. I would agree that this is part of the general Samaritan trend of making clarifying insertions and harmonizations in their texts, thus corrupting the textual integrity. Though I would note that the Sifrei need not be the 'source' for this harmonization, since it is a fairly straightforward, obvious, and indeed almost necessary harmonization. (Though I don't know whether Dr. Golomb was really suggesting this, in saying אף כי מקורו...)
It is these obvious instances of tampering to make the text more 'solid' that should caution us to be wary in less obvious instances. Even their Hebrew text is a Targum of sorts, and variations which seem to solve all our 'problems' in the masoretic text may have been the result of a deliberate hand.