Use a capturing group inside a lookahead. The lookahead captures the text you're interested in, but the actual match is technically the zero-width substring before the lookahead, so the matches are technically non-overlapping:
import re
s = "123456789123456789"
matches = re.finditer(r'(?=(d{10}))',s)
results = [int(match.group(1)) for match in matches]
# results:
# [1234567891,
# 2345678912,
# 3456789123,
# 4567891234,
# 5678912345,
# 6789123456,
# 7891234567,
# 8912345678,
# 9123456789]
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