How do I fix this error?

[KavinduShamalka]

error: duplicate lang item in crate std (which serde depends on): panic_impl.
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= note: the lang item is first defined in crate sp_io (which ocw_demo depends on)
= note: first definition in sp_io loaded from /home/kshamalka/recipes/target/release/wbuild/ocw-runtime/target/wasm32-unknown-unknown/release/deps/libsp_io-0713151cf511a047.rmeta
= note: second definition in std loaded from /home/kshamalka/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/lib/rustlib/wasm32-unknown-unknown/lib/libstd-4faf99cd6c5513da.rlib

error: duplicate lang item in crate std (which serde depends on): oom.
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= note: the lang item is first defined in crate sp_io (which ocw_demo depends on)
= note: first definition in sp_io loaded from /home/kshamalka/recipes/target/release/wbuild/ocw-runtime/target/wasm32-unknown-unknown/release/deps/libsp_io-0713151cf511a047.rmeta
= note: second definition in std loaded from /home/kshamalka/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/lib/rustlib/wasm32-unknown-unknown/lib/libstd-4faf99cd6c5513da.rlib

error: could not compile ocw-demo due to 2 previous errors
warning: build failed, waiting for other jobs to finish...