Why CMake C/C++ treats two binary library differently? (detail inside) - cmake

Question

Here's my CMake script:
cmake_minimum_required(VERSION 2.8)
project(cimutils)
set(CMAKE_CXX_STANDARD 11)
set(CMAKE_VERBOSE_MAKEFILE TRUE)
# not recommended to search for all *.c (This sets all source in variable SOURCES)
#file(GLOB_RECURSE SOURCES RELATIVE ${CMAKE_SOURCE_DIR} "*.c")
# explicitly define each .c file is preferred. (This sets all source in variable SOURCES)
set(SOURCES
"src/process_picture/saveraw.c"
"src/process_picture/savebmp.c"
"src/process_picture/savejpeg.c"
"src/lcd/framebuffer.c"
"src/main.c"
"src/cim/video.c"
"src/cim/process.c"
"src/cim/convert.c"
"src/cim/cim_fmt.c"
)
# set include path in variable INC
set (INC
"src/include"
"src/jpeg_hw_encoder"
)
# Set include path
include_directories (AFTER ${INC})
# Set all source files
add_executable(${PROJECT_NAME} ${SOURCES})
# Sets default (system) library path
set (CMAKE_SYSROOT "/usr/local/mips-linux-gnu-gcc-toolchains/mips-gcc-glibc/mips-linux-gnu/libc")
find_library (jpeg
NAMES jpeg
PATHS "${CMAKE_SOURCE_DIR}/lib"
)
find_library (jpeg-hw
NAMES jpeg-hw
PATHS "${CMAKE_SOURCE_DIR}/lib"
)
target_link_libraries(${PROJECT_NAME} c gcc_s ${jpeg} ${jpeg-hw})
The build is OK. However, it treated jpeg-hw and jpeg differently, since I saw the link command (detail truncated, to show only the relevant parts) to be:
gcc ..... ${PROJECT_HOME}/lib/libjpeg.so -ljpeg-hw
Apparently, these two binary libraries were placed in the same directory, and they uses the same syntax in the script file. But why CMake choose full path for one, and choose to use -l for the other? Just very curious....