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The Fostex E-2 is a 2-track/stereo mastering machine w/center-timecode track, that handles either 7" or 10.5" reels of 1/4" tape, running 7.5 & 15 ips.
The Fostex Model 20 is a 2-track/stereo mastering machine w/center-timecode track, that handles only 7" reels of 1/4" tape, running 7.5 & 15 ips.
The TEAC 3440 is a 4-track overdubbing deck with simul-sync.
Also, not mentioned,...
is
the Tascam 32, which is a 2-track/stereo mastering machine that handles either 7" or 10.5" reels of 1/4" tape, running 7.5 & 15 ips,...
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The Tascam 22-2, which is a 2-track/stereo mastering machine that handles only 7" reels of 1/4" tape, running 7.5 & 15 ips.
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For your stated purposes, you'd need either the Fostex E-2 / Tascam 32,... OR the Fostex Model 20 / Tascam 22-2, depending on whether you have small 7" reels or large 10.5" reels,... although the larger E-2 & 32 will handle both.
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The TEAC 3440 would not be suitable for your stated purpose.