Contradiction with Isaiah 2:12-13
Isaiah 2:12-13 speaks of the day of the LORD being against all cedars of Lebanon, while Isaiah 10:34 refers to them being cut down, which can be seen as contradictory in context.
Isaiah 2:12-13: For the day of the LORD of hosts [shall be] upon every [one that is] proud and lofty, and upon every [one that is] lifted up; and he shall be brought low:
Contradiction with Isaiah 35:1-2
These verses speak of Lebanon's glory and the flourishing of nature, contrasting Isaiah 10:34's imagery of destruction.
Isaiah 35:1-2: The wilderness and the solitary place shall be glad for them; and the desert shall rejoice, and blossom as the rose.