一直碰到这样的问题，请大家帮忙看看怎么回事，谢谢
Module <TX_crc32_data8> compiled
ERROR:HDLCompilers:27 - "CRC32_data8.v" line 8 Illegal redeclaration of 'crc32_data8'
Compiling verilog include file "de-mux_8to32.v"
Module <crc32_data8> compiled
ERROR:HDLCompilers:27 - "de-mux_8to32.v" line 3 Illegal redeclaration of 'demux_8to32'
Compiling verilog include file "RX_SOF_EOF_detect.v"
Module <demux_8to32> compiled
ERROR:HDLCompilers:27 - "RX_SOF_EOF_detect.v" line 3 Illegal redeclaration of 's_e_detect'

我用一个顶层模块，include了CRC32_data8.v，de-mux_8to32.v，RX_SOF_EOF_detect.v三个模块，可用xst综合时，每次都报这样的错误。
我用的是ISE8.2i

谢谢各位的解答