Avoid duplicated signatures when building transactions #1836

Job	Run time
build-binaries	11m 34s
check-packages	5m 53s
changelog	0s
build-wasm (wasm, build-wasm-scripts, wasm/tx_.wasm wasm/vp_.wasm wasm/checksums.json )	4m 3s
build-wasm (wasm-for-tests, build-wasm-tests-scripts, wasm_for_tests/*.wasm)	3m 30s
lints	5m 36s
rust-docs	6m 38s
test-ledger-app	7m 1s
test-wasm	7m 44s
test-unit	13m 29s
test-integration	22m 13s
check-benchmarks	0s
test-e2e	0s
test-e2e-with-device-automation	0s
upload-coverage	14s
	1h 27m 55s

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